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1.1 ! misho 1: <?xml version='1.0' encoding='ISO-8859-1' standalone='no'?> ! 2: <!DOCTYPE spec SYSTEM "dtds/spec.dtd" [ ! 3: ! 4: <!-- LAST TOUCHED BY: Tim Bray, 8 February 1997 --> ! 5: ! 6: <!-- The words 'FINAL EDIT' in comments mark places where changes ! 7: need to be made after approval of the document by the ERB, before ! 8: publication. --> ! 9: ! 10: <!ENTITY XML.version "1.0"> ! 11: <!ENTITY doc.date "10 February 1998"> ! 12: <!ENTITY iso6.doc.date "19980210"> ! 13: <!ENTITY w3c.doc.date "02-Feb-1998"> ! 14: <!ENTITY draft.day '10'> ! 15: <!ENTITY draft.month 'February'> ! 16: <!ENTITY draft.year '1998'> ! 17: ! 18: <!ENTITY WebSGML ! 19: 'WebSGML Adaptations Annex to ISO 8879'> ! 20: ! 21: <!ENTITY lt "<"> ! 22: <!ENTITY gt ">"> ! 23: <!ENTITY xmlpio "'<?xml'"> ! 24: <!ENTITY pic "'?>'"> ! 25: <!ENTITY br "\n"> ! 26: <!ENTITY cellback '#c0d9c0'> ! 27: <!ENTITY mdash "--"> <!-- —, but nsgmls doesn't grok hex --> ! 28: <!ENTITY com "--"> ! 29: <!ENTITY como "--"> ! 30: <!ENTITY comc "--"> ! 31: <!ENTITY hcro "&#x"> ! 32: <!-- <!ENTITY nbsp " "> --> ! 33: <!ENTITY nbsp " "> ! 34: <!ENTITY magicents "<code>amp</code>, ! 35: <code>lt</code>, ! 36: <code>gt</code>, ! 37: <code>apos</code>, ! 38: <code>quot</code>"> ! 39: ! 40: <!-- audience and distribution status: for use at publication time --> ! 41: <!ENTITY doc.audience "public review and discussion"> ! 42: <!ENTITY doc.distribution "may be distributed freely, as long as ! 43: all text and legal notices remain intact"> ! 44: ! 45: ]> ! 46: ! 47: <!-- for Panorama *--> ! 48: <?VERBATIM "eg" ?> ! 49: ! 50: <spec> ! 51: <header> ! 52: <title>Extensible Markup Language (XML) 1.0</title> ! 53: <version></version> ! 54: <w3c-designation>REC-xml-&iso6.doc.date;</w3c-designation> ! 55: <w3c-doctype>W3C Recommendation</w3c-doctype> ! 56: <pubdate><day>&draft.day;</day><month>&draft.month;</month><year>&draft.year;</year></pubdate> ! 57: ! 58: <publoc> ! 59: <loc href="http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;"> ! 60: http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;</loc> ! 61: <loc href="http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.xml"> ! 62: http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.xml</loc> ! 63: <loc href="http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.html"> ! 64: http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.html</loc> ! 65: <loc href="http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.pdf"> ! 66: http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.pdf</loc> ! 67: <loc href="http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.ps"> ! 68: http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.ps</loc> ! 69: </publoc> ! 70: <latestloc> ! 71: <loc href="http://www.w3.org/TR/REC-xml"> ! 72: http://www.w3.org/TR/REC-xml</loc> ! 73: </latestloc> ! 74: <prevlocs> ! 75: <loc href="http://www.w3.org/TR/PR-xml-971208"> ! 76: http://www.w3.org/TR/PR-xml-971208</loc> ! 77: <!-- ! 78: <loc href='http://www.w3.org/TR/WD-xml-961114'> ! 79: http://www.w3.org/TR/WD-xml-961114</loc> ! 80: <loc href='http://www.w3.org/TR/WD-xml-lang-970331'> ! 81: http://www.w3.org/TR/WD-xml-lang-970331</loc> ! 82: <loc href='http://www.w3.org/TR/WD-xml-lang-970630'> ! 83: http://www.w3.org/TR/WD-xml-lang-970630</loc> ! 84: <loc href='http://www.w3.org/TR/WD-xml-970807'> ! 85: http://www.w3.org/TR/WD-xml-970807</loc> ! 86: <loc href='http://www.w3.org/TR/WD-xml-971117'> ! 87: http://www.w3.org/TR/WD-xml-971117</loc>--> ! 88: </prevlocs> ! 89: <authlist> ! 90: <author><name>Tim Bray</name> ! 91: <affiliation>Textuality and Netscape</affiliation> ! 92: <email ! 93: href="mailto:tbray@textuality.com">tbray@textuality.com</email></author> ! 94: <author><name>Jean Paoli</name> ! 95: <affiliation>Microsoft</affiliation> ! 96: <email href="mailto:jeanpa@microsoft.com">jeanpa@microsoft.com</email></author> ! 97: <author><name>C. M. Sperberg-McQueen</name> ! 98: <affiliation>University of Illinois at Chicago</affiliation> ! 99: <email href="mailto:cmsmcq@uic.edu">cmsmcq@uic.edu</email></author> ! 100: </authlist> ! 101: <abstract> ! 102: <p>The Extensible Markup Language (XML) is a subset of ! 103: SGML that is completely described in this document. Its goal is to ! 104: enable generic SGML to be served, received, and processed on the Web ! 105: in the way that is now possible with HTML. XML has been designed for ! 106: ease of implementation and for interoperability with both SGML and ! 107: HTML.</p> ! 108: </abstract> ! 109: <status> ! 110: <p>This document has been reviewed by W3C Members and ! 111: other interested parties and has been endorsed by the ! 112: Director as a W3C Recommendation. It is a stable ! 113: document and may be used as reference material or cited ! 114: as a normative reference from another document. W3C's ! 115: role in making the Recommendation is to draw attention ! 116: to the specification and to promote its widespread ! 117: deployment. This enhances the functionality and ! 118: interoperability of the Web.</p> ! 119: <p> ! 120: This document specifies a syntax created by subsetting an existing, ! 121: widely used international text processing standard (Standard ! 122: Generalized Markup Language, ISO 8879:1986(E) as amended and ! 123: corrected) for use on the World Wide Web. It is a product of the W3C ! 124: XML Activity, details of which can be found at <loc ! 125: href='http://www.w3.org/XML'>http://www.w3.org/XML</loc>. A list of ! 126: current W3C Recommendations and other technical documents can be found ! 127: at <loc href='http://www.w3.org/TR'>http://www.w3.org/TR</loc>. ! 128: </p> ! 129: <p>This specification uses the term URI, which is defined by <bibref ! 130: ref="Berners-Lee"/>, a work in progress expected to update <bibref ! 131: ref="RFC1738"/> and <bibref ref="RFC1808"/>. ! 132: </p> ! 133: <p>The list of known errors in this specification is ! 134: available at ! 135: <loc href='http://www.w3.org/XML/xml-19980210-errata'>http://www.w3.org/XML/xml-19980210-errata</loc>.</p> ! 136: <p>Please report errors in this document to ! 137: <loc href='mailto:xml-editor@w3.org'>xml-editor@w3.org</loc>. ! 138: </p> ! 139: </status> ! 140: ! 141: ! 142: <pubstmt> ! 143: <p>Chicago, Vancouver, Mountain View, et al.: ! 144: World-Wide Web Consortium, XML Working Group, 1996, 1997.</p> ! 145: </pubstmt> ! 146: <sourcedesc> ! 147: <p>Created in electronic form.</p> ! 148: </sourcedesc> ! 149: <langusage> ! 150: <language id='EN'>English</language> ! 151: <language id='ebnf'>Extended Backus-Naur Form (formal grammar)</language> ! 152: </langusage> ! 153: <revisiondesc> ! 154: <slist> ! 155: <sitem>1997-12-03 : CMSMcQ : yet further changes</sitem> ! 156: <sitem>1997-12-02 : TB : further changes (see TB to XML WG, ! 157: 2 December 1997)</sitem> ! 158: <sitem>1997-12-02 : CMSMcQ : deal with as many corrections and ! 159: comments from the proofreaders as possible: ! 160: entify hard-coded document date in pubdate element, ! 161: change expansion of entity WebSGML, ! 162: update status description as per Dan Connolly (am not sure ! 163: about refernece to Berners-Lee et al.), ! 164: add 'The' to abstract as per WG decision, ! 165: move Relationship to Existing Standards to back matter and ! 166: combine with References, ! 167: re-order back matter so normative appendices come first, ! 168: re-tag back matter so informative appendices are tagged informdiv1, ! 169: remove XXX XXX from list of 'normative' specs in prose, ! 170: move some references from Other References to Normative References, ! 171: add RFC 1738, 1808, and 2141 to Other References (they are not ! 172: normative since we do not require the processor to enforce any ! 173: rules based on them), ! 174: add reference to 'Fielding draft' (Berners-Lee et al.), ! 175: move notation section to end of body, ! 176: drop URIchar non-terminal and use SkipLit instead, ! 177: lose stray reference to defunct nonterminal 'markupdecls', ! 178: move reference to Aho et al. into appendix (Tim's right), ! 179: add prose note saying that hash marks and fragment identifiers are ! 180: NOT part of the URI formally speaking, and are NOT legal in ! 181: system identifiers (processor 'may' signal an error). ! 182: Work through: ! 183: Tim Bray reacting to James Clark, ! 184: Tim Bray on his own, ! 185: Eve Maler, ! 186: ! 187: NOT DONE YET: ! 188: change binary / text to unparsed / parsed. ! 189: handle James's suggestion about < in attriubte values ! 190: uppercase hex characters, ! 191: namechar list, ! 192: </sitem> ! 193: <sitem>1997-12-01 : JB : add some column-width parameters</sitem> ! 194: <sitem>1997-12-01 : CMSMcQ : begin round of changes to incorporate ! 195: recent WG decisions and other corrections: ! 196: binding sources of character encoding info (27 Aug / 3 Sept), ! 197: correct wording of Faust quotation (restore dropped line), ! 198: drop SDD from EncodingDecl, ! 199: change text at version number 1.0, ! 200: drop misleading (wrong!) sentence about ignorables and extenders, ! 201: modify definition of PCData to make bar on msc grammatical, ! 202: change grammar's handling of internal subset (drop non-terminal markupdecls), ! 203: change definition of includeSect to allow conditional sections, ! 204: add integral-declaration constraint on internal subset, ! 205: drop misleading / dangerous sentence about relationship of ! 206: entities with system storage objects, ! 207: change table body tag to htbody as per EM change to DTD, ! 208: add rule about space normalization in public identifiers, ! 209: add description of how to generate our name-space rules from ! 210: Unicode character database (needs further work!). ! 211: </sitem> ! 212: <sitem>1997-10-08 : TB : Removed %-constructs again, new rules ! 213: for PE appearance.</sitem> ! 214: <sitem>1997-10-01 : TB : Case-sensitive markup; cleaned up ! 215: element-type defs, lotsa little edits for style</sitem> ! 216: <sitem>1997-09-25 : TB : Change to elm's new DTD, with ! 217: substantial detail cleanup as a side-effect</sitem> ! 218: <sitem>1997-07-24 : CMSMcQ : correct error (lost *) in definition ! 219: of ignoreSectContents (thanks to Makoto Murata)</sitem> ! 220: <sitem>Allow all empty elements to have end-tags, consistent with ! 221: SGML TC (as per JJC).</sitem> ! 222: <sitem>1997-07-23 : CMSMcQ : pre-emptive strike on pending corrections: ! 223: introduce the term 'empty-element tag', note that all empty elements ! 224: may use it, and elements declared EMPTY must use it. ! 225: Add WFC requiring encoding decl to come first in an entity. ! 226: Redefine notations to point to PIs as well as binary entities. ! 227: Change autodetection table by removing bytes 3 and 4 from ! 228: examples with Byte Order Mark. ! 229: Add content model as a term and clarify that it applies to both ! 230: mixed and element content. ! 231: </sitem> ! 232: <sitem>1997-06-30 : CMSMcQ : change date, some cosmetic changes, ! 233: changes to productions for choice, seq, Mixed, NotationType, ! 234: Enumeration. Follow James Clark's suggestion and prohibit ! 235: conditional sections in internal subset. TO DO: simplify ! 236: production for ignored sections as a result, since we don't ! 237: need to worry about parsers which don't expand PErefs finding ! 238: a conditional section.</sitem> ! 239: <sitem>1997-06-29 : TB : various edits</sitem> ! 240: <sitem>1997-06-29 : CMSMcQ : further changes: ! 241: Suppress old FINAL EDIT comments and some dead material. ! 242: Revise occurrences of % in grammar to exploit Henry Thompson's pun, ! 243: especially markupdecl and attdef. ! 244: Remove RMD requirement relating to element content (?). ! 245: </sitem> ! 246: <sitem>1997-06-28 : CMSMcQ : Various changes for 1 July draft: ! 247: Add text for draconian error handling (introduce ! 248: the term Fatal Error). ! 249: RE deleta est (changing wording from ! 250: original announcement to restrict the requirement to validating ! 251: parsers). ! 252: Tag definition of validating processor and link to it. ! 253: Add colon as name character. ! 254: Change def of %operator. ! 255: Change standard definitions of lt, gt, amp. ! 256: Strip leading zeros from #x00nn forms.</sitem> ! 257: <sitem>1997-04-02 : CMSMcQ : final corrections of editorial errors ! 258: found in last night's proofreading. Reverse course once more on ! 259: well-formed: Webster's Second hyphenates it, and that's enough ! 260: for me.</sitem> ! 261: <sitem>1997-04-01 : CMSMcQ : corrections from JJC, EM, HT, and self</sitem> ! 262: <sitem>1997-03-31 : Tim Bray : many changes</sitem> ! 263: <sitem>1997-03-29 : CMSMcQ : some Henry Thompson (on entity handling), ! 264: some Charles Goldfarb, some ERB decisions (PE handling in miscellaneous ! 265: declarations. Changed Ident element to accept def attribute. ! 266: Allow normalization of Unicode characters. move def of systemliteral ! 267: into section on literals.</sitem> ! 268: <sitem>1997-03-28 : CMSMcQ : make as many corrections as possible, from ! 269: Terry Allen, Norbert Mikula, James Clark, Jon Bosak, Henry Thompson, ! 270: Paul Grosso, and self. Among other things: give in on "well formed" ! 271: (Terry is right), tentatively rename QuotedCData as AttValue ! 272: and Literal as EntityValue to be more informative, since attribute ! 273: values are the <emph>only</emph> place QuotedCData was used, and ! 274: vice versa for entity text and Literal. (I'd call it Entity Text, ! 275: but 8879 uses that name for both internal and external entities.)</sitem> ! 276: <sitem>1997-03-26 : CMSMcQ : resynch the two forks of this draft, reapply ! 277: my changes dated 03-20 and 03-21. Normalize old 'may not' to 'must not' ! 278: except in the one case where it meant 'may or may not'.</sitem> ! 279: <sitem>1997-03-21 : TB : massive changes on plane flight from Chicago ! 280: to Vancouver</sitem> ! 281: <sitem>1997-03-21 : CMSMcQ : correct as many reported errors as possible. ! 282: </sitem> ! 283: <sitem>1997-03-20 : CMSMcQ : correct typos listed in CMSMcQ hand copy of spec.</sitem> ! 284: <sitem>1997-03-20 : CMSMcQ : cosmetic changes preparatory to revision for ! 285: WWW conference April 1997: restore some of the internal entity ! 286: references (e.g. to docdate, etc.), change character xA0 to &nbsp; ! 287: and define nbsp as &#160;, and refill a lot of paragraphs for ! 288: legibility.</sitem> ! 289: <sitem>1996-11-12 : CMSMcQ : revise using Tim's edits: ! 290: Add list type of NUMBERED and change most lists either to ! 291: BULLETS or to NUMBERED. ! 292: Suppress QuotedNames, Names (not used). ! 293: Correct trivial-grammar doc type decl. ! 294: Rename 'marked section' as 'CDATA section' passim. ! 295: Also edits from James Clark: ! 296: Define the set of characters from which [^abc] subtracts. ! 297: Charref should use just [0-9] not Digit. ! 298: Location info needs cleaner treatment: remove? (ERB ! 299: question). ! 300: One example of a PI has wrong pic. ! 301: Clarify discussion of encoding names. ! 302: Encoding failure should lead to unspecified results; don't ! 303: prescribe error recovery. ! 304: Don't require exposure of entity boundaries. ! 305: Ignore white space in element content. ! 306: Reserve entity names of the form u-NNNN. ! 307: Clarify relative URLs. ! 308: And some of my own: ! 309: Correct productions for content model: model cannot ! 310: consist of a name, so "elements ::= cp" is no good. ! 311: </sitem> ! 312: <sitem>1996-11-11 : CMSMcQ : revise for style. ! 313: Add new rhs to entity declaration, for parameter entities.</sitem> ! 314: <sitem>1996-11-10 : CMSMcQ : revise for style. ! 315: Fix / complete section on names, characters. ! 316: Add sections on parameter entities, conditional sections. ! 317: Still to do: Add compatibility note on deterministic content models. ! 318: Finish stylistic revision.</sitem> ! 319: <sitem>1996-10-31 : TB : Add Entity Handling section</sitem> ! 320: <sitem>1996-10-30 : TB : Clean up term & termdef. Slip in ! 321: ERB decision re EMPTY.</sitem> ! 322: <sitem>1996-10-28 : TB : Change DTD. Implement some of Michael's ! 323: suggestions. Change comments back to //. Introduce language for ! 324: XML namespace reservation. Add section on white-space handling. ! 325: Lots more cleanup.</sitem> ! 326: <sitem>1996-10-24 : CMSMcQ : quick tweaks, implement some ERB ! 327: decisions. Characters are not integers. Comments are /* */ not //. ! 328: Add bibliographic refs to 10646, HyTime, Unicode. ! 329: Rename old Cdata as MsData since it's <emph>only</emph> seen ! 330: in marked sections. Call them attribute-value pairs not ! 331: name-value pairs, except once. Internal subset is optional, needs ! 332: '?'. Implied attributes should be signaled to the app, not ! 333: have values supplied by processor.</sitem> ! 334: <sitem>1996-10-16 : TB : track down & excise all DSD references; ! 335: introduce some EBNF for entity declarations.</sitem> ! 336: <sitem>1996-10-?? : TB : consistency check, fix up scraps so ! 337: they all parse, get formatter working, correct a few productions.</sitem> ! 338: <sitem>1996-10-10/11 : CMSMcQ : various maintenance, stylistic, and ! 339: organizational changes: ! 340: Replace a few literals with xmlpio and ! 341: pic entities, to make them consistent and ensure we can change pic ! 342: reliably when the ERB votes. ! 343: Drop paragraph on recognizers from notation section. ! 344: Add match, exact match to terminology. ! 345: Move old 2.2 XML Processors and Apps into intro. ! 346: Mention comments, PIs, and marked sections in discussion of ! 347: delimiter escaping. ! 348: Streamline discussion of doctype decl syntax. ! 349: Drop old section of 'PI syntax' for doctype decl, and add ! 350: section on partial-DTD summary PIs to end of Logical Structures ! 351: section. ! 352: Revise DSD syntax section to use Tim's subset-in-a-PI ! 353: mechanism.</sitem> ! 354: <sitem>1996-10-10 : TB : eliminate name recognizers (and more?)</sitem> ! 355: <sitem>1996-10-09 : CMSMcQ : revise for style, consistency through 2.3 ! 356: (Characters)</sitem> ! 357: <sitem>1996-10-09 : CMSMcQ : re-unite everything for convenience, ! 358: at least temporarily, and revise quickly</sitem> ! 359: <sitem>1996-10-08 : TB : first major homogenization pass</sitem> ! 360: <sitem>1996-10-08 : TB : turn "current" attribute on div type into ! 361: CDATA</sitem> ! 362: <sitem>1996-10-02 : TB : remould into skeleton + entities</sitem> ! 363: <sitem>1996-09-30 : CMSMcQ : add a few more sections prior to exchange ! 364: with Tim.</sitem> ! 365: <sitem>1996-09-20 : CMSMcQ : finish transcribing notes.</sitem> ! 366: <sitem>1996-09-19 : CMSMcQ : begin transcribing notes for draft.</sitem> ! 367: <sitem>1996-09-13 : CMSMcQ : made outline from notes of 09-06, ! 368: do some housekeeping</sitem> ! 369: </slist> ! 370: </revisiondesc> ! 371: </header> ! 372: <body> ! 373: <div1 id='sec-intro'> ! 374: <head>Introduction</head> ! 375: <p>Extensible Markup Language, abbreviated XML, describes a class of ! 376: data objects called <termref def="dt-xml-doc">XML documents</termref> and ! 377: partially describes the behavior of ! 378: computer programs which process them. XML is an application profile or ! 379: restricted form of SGML, the Standard Generalized Markup ! 380: Language <bibref ref='ISO8879'/>. ! 381: By construction, XML documents ! 382: are conforming SGML documents. ! 383: </p> ! 384: <p>XML documents are made up of storage units called <termref ! 385: def="dt-entity">entities</termref>, which contain either parsed ! 386: or unparsed data. ! 387: Parsed data is made up of <termref def="dt-character">characters</termref>, ! 388: some ! 389: of which form <termref def="dt-chardata">character data</termref>, ! 390: and some of which form <termref def="dt-markup">markup</termref>. ! 391: Markup encodes a description of the document's storage layout and ! 392: logical structure. XML provides a mechanism to impose constraints on ! 393: the storage layout and logical structure.</p> ! 394: <p><termdef id="dt-xml-proc" term="XML Processor">A software module ! 395: called an <term>XML processor</term> is used to read XML documents ! 396: and provide access to their content and structure.</termdef> <termdef ! 397: id="dt-app" term="Application">It is assumed that an XML processor is ! 398: doing its work on behalf of another module, called the ! 399: <term>application</term>.</termdef> This specification describes the ! 400: required behavior of an XML processor in terms of how it must read XML ! 401: data and the information it must provide to the application.</p> ! 402: ! 403: <div2 id='sec-origin-goals'> ! 404: <head>Origin and Goals</head> ! 405: <p>XML was developed by an XML Working Group (originally known as the ! 406: SGML Editorial Review Board) formed under the auspices of the World ! 407: Wide Web Consortium (W3C) in 1996. ! 408: It was chaired by Jon Bosak of Sun ! 409: Microsystems with the active participation of an XML Special ! 410: Interest Group (previously known as the SGML Working Group) also ! 411: organized by the W3C. The membership of the XML Working Group is given ! 412: in an appendix. Dan Connolly served as the WG's contact with the W3C. ! 413: </p> ! 414: <p>The design goals for XML are:<olist> ! 415: <item><p>XML shall be straightforwardly usable over the ! 416: Internet.</p></item> ! 417: <item><p>XML shall support a wide variety of applications.</p></item> ! 418: <item><p>XML shall be compatible with SGML.</p></item> ! 419: <item><p>It shall be easy to write programs which process XML ! 420: documents.</p></item> ! 421: <item><p>The number of optional features in XML is to be kept to the ! 422: absolute minimum, ideally zero.</p></item> ! 423: <item><p>XML documents should be human-legible and reasonably ! 424: clear.</p></item> ! 425: <item><p>The XML design should be prepared quickly.</p></item> ! 426: <item><p>The design of XML shall be formal and concise.</p></item> ! 427: <item><p>XML documents shall be easy to create.</p></item> ! 428: <item><p>Terseness in XML markup is of minimal importance.</p></item></olist> ! 429: </p> ! 430: <p>This specification, ! 431: together with associated standards ! 432: (Unicode and ISO/IEC 10646 for characters, ! 433: Internet RFC 1766 for language identification tags, ! 434: ISO 639 for language name codes, and ! 435: ISO 3166 for country name codes), ! 436: provides all the information necessary to understand ! 437: XML Version &XML.version; ! 438: and construct computer programs to process it.</p> ! 439: <p>This version of the XML specification ! 440: <!-- is for &doc.audience;.--> ! 441: &doc.distribution;.</p> ! 442: ! 443: </div2> ! 444: ! 445: ! 446: ! 447: ! 448: <div2 id='sec-terminology'> ! 449: <head>Terminology</head> ! 450: ! 451: <p>The terminology used to describe XML documents is defined in the body of ! 452: this specification. ! 453: The terms defined in the following list are used in building those ! 454: definitions and in describing the actions of an XML processor: ! 455: <glist> ! 456: <gitem> ! 457: <label>may</label> ! 458: <def><p><termdef id="dt-may" term="May">Conforming documents and XML ! 459: processors are permitted to but need not behave as ! 460: described.</termdef></p></def> ! 461: </gitem> ! 462: <gitem> ! 463: <label>must</label> ! 464: <def><p>Conforming documents and XML processors ! 465: are required to behave as described; otherwise they are in error. ! 466: <!-- do NOT change this! this is what defines a violation of ! 467: a 'must' clause as 'an error'. -MSM --> ! 468: </p></def> ! 469: </gitem> ! 470: <gitem> ! 471: <label>error</label> ! 472: <def><p><termdef id='dt-error' term='Error' ! 473: >A violation of the rules of this ! 474: specification; results are ! 475: undefined. Conforming software may detect and report an error and may ! 476: recover from it.</termdef></p></def> ! 477: </gitem> ! 478: <gitem> ! 479: <label>fatal error</label> ! 480: <def><p><termdef id="dt-fatal" term="Fatal Error">An error ! 481: which a conforming <termref def="dt-xml-proc">XML processor</termref> ! 482: must detect and report to the application. ! 483: After encountering a fatal error, the ! 484: processor may continue ! 485: processing the data to search for further errors and may report such ! 486: errors to the application. In order to support correction of errors, ! 487: the processor may make unprocessed data from the document (with ! 488: intermingled character data and markup) available to the application. ! 489: Once a fatal error is detected, however, the processor must not ! 490: continue normal processing (i.e., it must not ! 491: continue to pass character data and information about the document's ! 492: logical structure to the application in the normal way). ! 493: </termdef></p></def> ! 494: </gitem> ! 495: <gitem> ! 496: <label>at user option</label> ! 497: <def><p>Conforming software may or must (depending on the modal verb in the ! 498: sentence) behave as described; if it does, it must ! 499: provide users a means to enable or disable the behavior ! 500: described.</p></def> ! 501: </gitem> ! 502: <gitem> ! 503: <label>validity constraint</label> ! 504: <def><p>A rule which applies to all ! 505: <termref def="dt-valid">valid</termref> XML documents. ! 506: Violations of validity constraints are errors; they must, at user option, ! 507: be reported by ! 508: <termref def="dt-validating">validating XML processors</termref>.</p></def> ! 509: </gitem> ! 510: <gitem> ! 511: <label>well-formedness constraint</label> ! 512: <def><p>A rule which applies to all <termref ! 513: def="dt-wellformed">well-formed</termref> XML documents. ! 514: Violations of well-formedness constraints are ! 515: <termref def="dt-fatal">fatal errors</termref>.</p></def> ! 516: </gitem> ! 517: ! 518: <gitem> ! 519: <label>match</label> ! 520: <def><p><termdef id="dt-match" term="match">(Of strings or names:) ! 521: Two strings or names being compared must be identical. ! 522: Characters with multiple possible representations in ISO/IEC 10646 (e.g. ! 523: characters with ! 524: both precomposed and base+diacritic forms) match only if they have the ! 525: same representation in both strings. ! 526: At user option, processors may normalize such characters to ! 527: some canonical form. ! 528: No case folding is performed. ! 529: (Of strings and rules in the grammar:) ! 530: A string matches a grammatical production if it belongs to the ! 531: language generated by that production. ! 532: (Of content and content models:) ! 533: An element matches its declaration when it conforms ! 534: in the fashion described in the constraint ! 535: <specref ref='elementvalid'/>. ! 536: </termdef> ! 537: </p></def> ! 538: </gitem> ! 539: <gitem> ! 540: <label>for compatibility</label> ! 541: <def><p><termdef id="dt-compat" term="For Compatibility">A feature of ! 542: XML included solely to ensure that XML remains compatible with SGML. ! 543: </termdef></p></def> ! 544: </gitem> ! 545: <gitem> ! 546: <label>for interoperability</label> ! 547: <def><p><termdef id="dt-interop" term="For interoperability">A ! 548: non-binding recommendation included to increase the chances that XML ! 549: documents can be processed by the existing installed base of SGML ! 550: processors which predate the ! 551: &WebSGML;.</termdef></p></def> ! 552: </gitem> ! 553: </glist> ! 554: </p> ! 555: </div2> ! 556: ! 557: ! 558: </div1> ! 559: <!-- &Docs; --> ! 560: ! 561: <div1 id='sec-documents'> ! 562: <head>Documents</head> ! 563: ! 564: <p><termdef id="dt-xml-doc" term="XML Document"> ! 565: A data object is an ! 566: <term>XML document</term> if it is ! 567: <termref def="dt-wellformed">well-formed</termref>, as ! 568: defined in this specification. ! 569: A well-formed XML document may in addition be ! 570: <termref def="dt-valid">valid</termref> if it meets certain further ! 571: constraints.</termdef></p> ! 572: ! 573: <p>Each XML document has both a logical and a physical structure. ! 574: Physically, the document is composed of units called <termref ! 575: def="dt-entity">entities</termref>. An entity may <termref ! 576: def="dt-entref">refer</termref> to other entities to cause their ! 577: inclusion in the document. A document begins in a "root" or <termref ! 578: def="dt-docent">document entity</termref>. ! 579: Logically, the document is composed of declarations, elements, ! 580: comments, ! 581: character references, and ! 582: processing ! 583: instructions, all of which are indicated in the document by explicit ! 584: markup. ! 585: The logical and physical structures must nest properly, as described ! 586: in <specref ref='wf-entities'/>. ! 587: </p> ! 588: ! 589: <div2 id='sec-well-formed'> ! 590: <head>Well-Formed XML Documents</head> ! 591: ! 592: <p><termdef id="dt-wellformed" term="Well-Formed"> ! 593: A textual object is ! 594: a well-formed XML document if:</termdef> ! 595: <olist> ! 596: <item><p>Taken as a whole, it ! 597: matches the production labeled <nt def='NT-document'>document</nt>.</p></item> ! 598: <item><p>It ! 599: meets all the well-formedness constraints given in this specification.</p> ! 600: </item> ! 601: <item><p>Each of the <termref def='dt-parsedent'>parsed entities</termref> ! 602: which is referenced directly or indirectly within the document is ! 603: <titleref href='wf-entities'>well-formed</titleref>.</p></item> ! 604: </olist></p> ! 605: <p> ! 606: <scrap lang='ebnf' id='document'> ! 607: <head>Document</head> ! 608: <prod id='NT-document'><lhs>document</lhs> ! 609: <rhs><nt def='NT-prolog'>prolog</nt> ! 610: <nt def='NT-element'>element</nt> ! 611: <nt def='NT-Misc'>Misc</nt>*</rhs></prod> ! 612: </scrap> ! 613: </p> ! 614: <p>Matching the <nt def="NT-document">document</nt> production ! 615: implies that: ! 616: <olist> ! 617: <item><p>It contains one or more ! 618: <termref def="dt-element">elements</termref>.</p> ! 619: </item> ! 620: <!--* N.B. some readers (notably JC) find the following ! 621: paragraph awkward and redundant. I agree it's logically redundant: ! 622: it *says* it is summarizing the logical implications of ! 623: matching the grammar, and that means by definition it's ! 624: logically redundant. I don't think it's rhetorically ! 625: redundant or unnecessary, though, so I'm keeping it. It ! 626: could however use some recasting when the editors are feeling ! 627: stronger. -MSM *--> ! 628: <item><p><termdef id="dt-root" term="Root Element">There is exactly ! 629: one element, called the <term>root</term>, or document element, no ! 630: part of which appears in the <termref ! 631: def="dt-content">content</termref> of any other element.</termdef> ! 632: For all other elements, if the start-tag is in the content of another ! 633: element, the end-tag is in the content of the same element. More ! 634: simply stated, the elements, delimited by start- and end-tags, nest ! 635: properly within each other. ! 636: </p></item> ! 637: </olist> ! 638: </p> ! 639: <p><termdef id="dt-parentchild" term="Parent/Child">As a consequence ! 640: of this, ! 641: for each non-root element ! 642: <code>C</code> in the document, there is one other element <code>P</code> ! 643: in the document such that ! 644: <code>C</code> is in the content of <code>P</code>, but is not in ! 645: the content of any other element that is in the content of ! 646: <code>P</code>. ! 647: <code>P</code> is referred to as the ! 648: <term>parent</term> of <code>C</code>, and <code>C</code> as a ! 649: <term>child</term> of <code>P</code>.</termdef></p></div2> ! 650: ! 651: <div2 id="charsets"> ! 652: <head>Characters</head> ! 653: ! 654: <p><termdef id="dt-text" term="Text">A parsed entity contains ! 655: <term>text</term>, a sequence of ! 656: <termref def="dt-character">characters</termref>, ! 657: which may represent markup or character data.</termdef> ! 658: <termdef id="dt-character" term="Character">A <term>character</term> ! 659: is an atomic unit of text as specified by ! 660: ISO/IEC 10646 <bibref ref="ISO10646"/>. ! 661: Legal characters are tab, carriage return, line feed, and the legal ! 662: graphic characters of Unicode and ISO/IEC 10646. ! 663: The use of "compatibility characters", as defined in section 6.8 ! 664: of <bibref ref='Unicode'/>, is discouraged. ! 665: </termdef> ! 666: <scrap lang="ebnf" id="char32"> ! 667: <head>Character Range</head> ! 668: <prodgroup pcw2="4" pcw4="17.5" pcw5="11"> ! 669: <prod id="NT-Char"><lhs>Char</lhs> ! 670: <rhs>#x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] ! 671: | [#x10000-#x10FFFF]</rhs> ! 672: <com>any Unicode character, excluding the ! 673: surrogate blocks, FFFE, and FFFF.</com> </prod> ! 674: </prodgroup> ! 675: </scrap> ! 676: </p> ! 677: ! 678: <p>The mechanism for encoding character code points into bit patterns may ! 679: vary from entity to entity. All XML processors must accept the UTF-8 ! 680: and UTF-16 encodings of 10646; the mechanisms for signaling which of ! 681: the two is in use, or for bringing other encodings into play, are ! 682: discussed later, in <specref ref='charencoding'/>. ! 683: </p> ! 684: <!-- ! 685: <p>Regardless of the specific encoding used, any character in the ISO/IEC ! 686: 10646 character set may be referred to by the decimal or hexadecimal ! 687: equivalent of its ! 688: UCS-4 code value. ! 689: </p>--> ! 690: </div2> ! 691: ! 692: <div2 id='sec-common-syn'> ! 693: <head>Common Syntactic Constructs</head> ! 694: ! 695: <p>This section defines some symbols used widely in the grammar.</p> ! 696: <p><nt def="NT-S">S</nt> (white space) consists of one or more space (#x20) ! 697: characters, carriage returns, line feeds, or tabs. ! 698: ! 699: <scrap lang="ebnf" id='white'> ! 700: <head>White Space</head> ! 701: <prodgroup pcw2="4" pcw4="17.5" pcw5="11"> ! 702: <prod id='NT-S'><lhs>S</lhs> ! 703: <rhs>(#x20 | #x9 | #xD | #xA)+</rhs> ! 704: </prod> ! 705: </prodgroup> ! 706: </scrap></p> ! 707: <p>Characters are classified for convenience as letters, digits, or other ! 708: characters. Letters consist of an alphabetic or syllabic ! 709: base character possibly ! 710: followed by one or more combining characters, or of an ideographic ! 711: character. ! 712: Full definitions of the specific characters in each class ! 713: are given in <specref ref='CharClasses'/>.</p> ! 714: <p><termdef id="dt-name" term="Name">A <term>Name</term> is a token ! 715: beginning with a letter or one of a few punctuation characters, and continuing ! 716: with letters, digits, hyphens, underscores, colons, or full stops, together ! 717: known as name characters.</termdef> ! 718: Names beginning with the string "<code>xml</code>", or any string ! 719: which would match <code>(('X'|'x') ('M'|'m') ('L'|'l'))</code>, are ! 720: reserved for standardization in this or future versions of this ! 721: specification. ! 722: </p> ! 723: <note> ! 724: <p>The colon character within XML names is reserved for experimentation with ! 725: name spaces. ! 726: Its meaning is expected to be ! 727: standardized at some future point, at which point those documents ! 728: using the colon for experimental purposes may need to be updated. ! 729: (There is no guarantee that any name-space mechanism ! 730: adopted for XML will in fact use the colon as a name-space delimiter.) ! 731: In practice, this means that authors should not use the colon in XML ! 732: names except as part of name-space experiments, but that XML processors ! 733: should accept the colon as a name character.</p> ! 734: </note> ! 735: <p>An ! 736: <nt def='NT-Nmtoken'>Nmtoken</nt> (name token) is any mixture of ! 737: name characters. ! 738: <scrap lang='ebnf'> ! 739: <head>Names and Tokens</head> ! 740: <prod id='NT-NameChar'><lhs>NameChar</lhs> ! 741: <rhs><nt def="NT-Letter">Letter</nt> ! 742: | <nt def='NT-Digit'>Digit</nt> ! 743: | '.' | '-' | '_' | ':' ! 744: | <nt def='NT-CombiningChar'>CombiningChar</nt> ! 745: | <nt def='NT-Extender'>Extender</nt></rhs> ! 746: </prod> ! 747: <prod id='NT-Name'><lhs>Name</lhs> ! 748: <rhs>(<nt def='NT-Letter'>Letter</nt> | '_' | ':') ! 749: (<nt def='NT-NameChar'>NameChar</nt>)*</rhs></prod> ! 750: <prod id='NT-Names'><lhs>Names</lhs> ! 751: <rhs><nt def='NT-Name'>Name</nt> ! 752: (<nt def='NT-S'>S</nt> <nt def='NT-Name'>Name</nt>)*</rhs></prod> ! 753: <prod id='NT-Nmtoken'><lhs>Nmtoken</lhs> ! 754: <rhs>(<nt def='NT-NameChar'>NameChar</nt>)+</rhs></prod> ! 755: <prod id='NT-Nmtokens'><lhs>Nmtokens</lhs> ! 756: <rhs><nt def='NT-Nmtoken'>Nmtoken</nt> (<nt def='NT-S'>S</nt> <nt def='NT-Nmtoken'>Nmtoken</nt>)*</rhs></prod> ! 757: </scrap> ! 758: </p> ! 759: <p>Literal data is any quoted string not containing ! 760: the quotation mark used as a delimiter for that string. ! 761: Literals are used ! 762: for specifying the content of internal entities ! 763: (<nt def='NT-EntityValue'>EntityValue</nt>), ! 764: the values of attributes (<nt def='NT-AttValue'>AttValue</nt>), ! 765: and external identifiers ! 766: (<nt def="NT-SystemLiteral">SystemLiteral</nt>). ! 767: Note that a <nt def='NT-SystemLiteral'>SystemLiteral</nt> ! 768: can be parsed without scanning for markup. ! 769: <scrap lang='ebnf'> ! 770: <head>Literals</head> ! 771: <prod id='NT-EntityValue'><lhs>EntityValue</lhs> ! 772: <rhs>'"' ! 773: ([^%&"] ! 774: | <nt def='NT-PEReference'>PEReference</nt> ! 775: | <nt def='NT-Reference'>Reference</nt>)* ! 776: '"' ! 777: </rhs> ! 778: <rhs>| ! 779: "'" ! 780: ([^%&'] ! 781: | <nt def='NT-PEReference'>PEReference</nt> ! 782: | <nt def='NT-Reference'>Reference</nt>)* ! 783: "'"</rhs> ! 784: </prod> ! 785: <prod id='NT-AttValue'><lhs>AttValue</lhs> ! 786: <rhs>'"' ! 787: ([^<&"] ! 788: | <nt def='NT-Reference'>Reference</nt>)* ! 789: '"' ! 790: </rhs> ! 791: <rhs>| ! 792: "'" ! 793: ([^<&'] ! 794: | <nt def='NT-Reference'>Reference</nt>)* ! 795: "'"</rhs> ! 796: </prod> ! 797: <prod id="NT-SystemLiteral"><lhs>SystemLiteral</lhs> ! 798: <rhs>('"' [^"]* '"') | ("'" [^']* "'") ! 799: </rhs> ! 800: </prod> ! 801: <prod id="NT-PubidLiteral"><lhs>PubidLiteral</lhs> ! 802: <rhs>'"' <nt def='NT-PubidChar'>PubidChar</nt>* ! 803: '"' ! 804: | "'" (<nt def='NT-PubidChar'>PubidChar</nt> - "'")* "'"</rhs> ! 805: </prod> ! 806: <prod id="NT-PubidChar"><lhs>PubidChar</lhs> ! 807: <rhs>#x20 | #xD | #xA ! 808: | [a-zA-Z0-9] ! 809: | [-'()+,./:=?;!*#@$_%]</rhs> ! 810: </prod> ! 811: </scrap> ! 812: </p> ! 813: ! 814: </div2> ! 815: ! 816: <div2 id='syntax'> ! 817: <head>Character Data and Markup</head> ! 818: ! 819: <p><termref def='dt-text'>Text</termref> consists of intermingled ! 820: <termref def="dt-chardata">character ! 821: data</termref> and markup. ! 822: <termdef id="dt-markup" term="Markup"><term>Markup</term> takes the form of ! 823: <termref def="dt-stag">start-tags</termref>, ! 824: <termref def="dt-etag">end-tags</termref>, ! 825: <termref def="dt-empty">empty-element tags</termref>, ! 826: <termref def="dt-entref">entity references</termref>, ! 827: <termref def="dt-charref">character references</termref>, ! 828: <termref def="dt-comment">comments</termref>, ! 829: <termref def="dt-cdsection">CDATA section</termref> delimiters, ! 830: <termref def="dt-doctype">document type declarations</termref>, and ! 831: <termref def="dt-pi">processing instructions</termref>. ! 832: </termdef> ! 833: </p> ! 834: <p><termdef id="dt-chardata" term="Character Data">All text that is not markup ! 835: constitutes the <term>character data</term> of ! 836: the document.</termdef></p> ! 837: <p>The ampersand character (&) and the left angle bracket (<) ! 838: may appear in their literal form <emph>only</emph> when used as markup ! 839: delimiters, or within a <termref def="dt-comment">comment</termref>, a ! 840: <termref def="dt-pi">processing instruction</termref>, ! 841: or a <termref def="dt-cdsection">CDATA section</termref>. ! 842: ! 843: They are also legal within the <termref def='dt-litentval'>literal entity ! 844: value</termref> of an internal entity declaration; see ! 845: <specref ref='wf-entities'/>. ! 846: <!-- FINAL EDIT: restore internal entity decl or leave it out. --> ! 847: If they are needed elsewhere, ! 848: they must be <termref def="dt-escape">escaped</termref> ! 849: using either <termref def='dt-charref'>numeric character references</termref> ! 850: or the strings ! 851: "<code>&amp;</code>" and "<code>&lt;</code>" respectively. ! 852: The right angle ! 853: bracket (>) may be represented using the string ! 854: "<code>&gt;</code>", and must, <termref def='dt-compat'>for ! 855: compatibility</termref>, ! 856: be escaped using ! 857: "<code>&gt;</code>" or a character reference ! 858: when it appears in the string ! 859: "<code>]]></code>" ! 860: in content, ! 861: when that string is not marking the end of ! 862: a <termref def="dt-cdsection">CDATA section</termref>. ! 863: </p> ! 864: <p> ! 865: In the content of elements, character data ! 866: is any string of characters which does ! 867: not contain the start-delimiter of any markup. ! 868: In a CDATA section, character data ! 869: is any string of characters not including the CDATA-section-close ! 870: delimiter, "<code>]]></code>".</p> ! 871: <p> ! 872: To allow attribute values to contain both single and double quotes, the ! 873: apostrophe or single-quote character (') may be represented as ! 874: "<code>&apos;</code>", and the double-quote character (") as ! 875: "<code>&quot;</code>". ! 876: <scrap lang="ebnf"> ! 877: <head>Character Data</head> ! 878: <prod id='NT-CharData'> ! 879: <lhs>CharData</lhs> ! 880: <rhs>[^<&]* - ([^<&]* ']]>' [^<&]*)</rhs> ! 881: </prod> ! 882: </scrap> ! 883: </p> ! 884: </div2> ! 885: ! 886: <div2 id='sec-comments'> ! 887: <head>Comments</head> ! 888: ! 889: <p><termdef id="dt-comment" term="Comment"><term>Comments</term> may ! 890: appear anywhere in a document outside other ! 891: <termref def='dt-markup'>markup</termref>; in addition, ! 892: they may appear within the document type declaration ! 893: at places allowed by the grammar. ! 894: They are not part of the document's <termref def="dt-chardata">character ! 895: data</termref>; an XML ! 896: processor may, but need not, make it possible for an application to ! 897: retrieve the text of comments. ! 898: <termref def="dt-compat">For compatibility</termref>, the string ! 899: "<code>--</code>" (double-hyphen) must not occur within ! 900: comments. ! 901: <scrap lang="ebnf"> ! 902: <head>Comments</head> ! 903: <prod id='NT-Comment'><lhs>Comment</lhs> ! 904: <rhs>'<!--' ! 905: ((<nt def='NT-Char'>Char</nt> - '-') ! 906: | ('-' (<nt def='NT-Char'>Char</nt> - '-')))* ! 907: '-->'</rhs> ! 908: </prod> ! 909: </scrap> ! 910: </termdef></p> ! 911: <p>An example of a comment: ! 912: <eg><!&como; declarations for <head> & <body> &comc;></eg> ! 913: </p> ! 914: </div2> ! 915: ! 916: <div2 id='sec-pi'> ! 917: <head>Processing Instructions</head> ! 918: ! 919: <p><termdef id="dt-pi" term="Processing instruction"><term>Processing ! 920: instructions</term> (PIs) allow documents to contain instructions ! 921: for applications. ! 922: ! 923: <scrap lang="ebnf"> ! 924: <head>Processing Instructions</head> ! 925: <prod id='NT-PI'><lhs>PI</lhs> ! 926: <rhs>'<?' <nt def='NT-PITarget'>PITarget</nt> ! 927: (<nt def='NT-S'>S</nt> ! 928: (<nt def='NT-Char'>Char</nt>* - ! 929: (<nt def='NT-Char'>Char</nt>* &pic; <nt def='NT-Char'>Char</nt>*)))? ! 930: &pic;</rhs></prod> ! 931: <prod id='NT-PITarget'><lhs>PITarget</lhs> ! 932: <rhs><nt def='NT-Name'>Name</nt> - ! 933: (('X' | 'x') ('M' | 'm') ('L' | 'l'))</rhs> ! 934: </prod> ! 935: </scrap></termdef> ! 936: PIs are not part of the document's <termref def="dt-chardata">character ! 937: data</termref>, but must be passed through to the application. The ! 938: PI begins with a target (<nt def='NT-PITarget'>PITarget</nt>) used ! 939: to identify the application to which the instruction is directed. ! 940: The target names "<code>XML</code>", "<code>xml</code>", and so on are ! 941: reserved for standardization in this or future versions of this ! 942: specification. ! 943: The ! 944: XML <termref def='dt-notation'>Notation</termref> mechanism ! 945: may be used for ! 946: formal declaration of PI targets. ! 947: </p> ! 948: </div2> ! 949: ! 950: <div2 id='sec-cdata-sect'> ! 951: <head>CDATA Sections</head> ! 952: ! 953: <p><termdef id="dt-cdsection" term="CDATA Section"><term>CDATA sections</term> ! 954: may occur ! 955: anywhere character data may occur; they are ! 956: used to escape blocks of text containing characters which would ! 957: otherwise be recognized as markup. CDATA sections begin with the ! 958: string "<code><![CDATA[</code>" and end with the string ! 959: "<code>]]></code>": ! 960: <scrap lang="ebnf"> ! 961: <head>CDATA Sections</head> ! 962: <prod id='NT-CDSect'><lhs>CDSect</lhs> ! 963: <rhs><nt def='NT-CDStart'>CDStart</nt> ! 964: <nt def='NT-CData'>CData</nt> ! 965: <nt def='NT-CDEnd'>CDEnd</nt></rhs></prod> ! 966: <prod id='NT-CDStart'><lhs>CDStart</lhs> ! 967: <rhs>'<![CDATA['</rhs> ! 968: </prod> ! 969: <prod id='NT-CData'><lhs>CData</lhs> ! 970: <rhs>(<nt def='NT-Char'>Char</nt>* - ! 971: (<nt def='NT-Char'>Char</nt>* ']]>' <nt def='NT-Char'>Char</nt>*)) ! 972: </rhs> ! 973: </prod> ! 974: <prod id='NT-CDEnd'><lhs>CDEnd</lhs> ! 975: <rhs>']]>'</rhs> ! 976: </prod> ! 977: </scrap> ! 978: ! 979: Within a CDATA section, only the <nt def='NT-CDEnd'>CDEnd</nt> string is ! 980: recognized as markup, so that left angle brackets and ampersands may occur in ! 981: their literal form; they need not (and cannot) be escaped using ! 982: "<code>&lt;</code>" and "<code>&amp;</code>". CDATA sections ! 983: cannot nest.</termdef> ! 984: </p> ! 985: ! 986: <p>An example of a CDATA section, in which "<code><greeting></code>" and ! 987: "<code></greeting></code>" ! 988: are recognized as <termref def='dt-chardata'>character data</termref>, not ! 989: <termref def='dt-markup'>markup</termref>: ! 990: <eg><![CDATA[<greeting>Hello, world!</greeting>]]></eg> ! 991: </p> ! 992: </div2> ! 993: ! 994: <div2 id='sec-prolog-dtd'> ! 995: <head>Prolog and Document Type Declaration</head> ! 996: ! 997: <p><termdef id='dt-xmldecl' term='XML Declaration'>XML documents ! 998: may, and should, ! 999: begin with an <term>XML declaration</term> which specifies ! 1000: the version of ! 1001: XML being used.</termdef> ! 1002: For example, the following is a complete XML document, <termref ! 1003: def="dt-wellformed">well-formed</termref> but not ! 1004: <termref def="dt-valid">valid</termref>: ! 1005: <eg><![CDATA[<?xml version="1.0"?> ! 1006: <greeting>Hello, world!</greeting> ! 1007: ]]></eg> ! 1008: and so is this: ! 1009: <eg><![CDATA[<greeting>Hello, world!</greeting> ! 1010: ]]></eg> ! 1011: </p> ! 1012: ! 1013: <p>The version number "<code>1.0</code>" should be used to indicate ! 1014: conformance to this version of this specification; it is an error ! 1015: for a document to use the value "<code>1.0</code>" ! 1016: if it does not conform to this version of this specification. ! 1017: It is the intent ! 1018: of the XML working group to give later versions of this specification ! 1019: numbers other than "<code>1.0</code>", but this intent does not ! 1020: indicate a ! 1021: commitment to produce any future versions of XML, nor if any are produced, to ! 1022: use any particular numbering scheme. ! 1023: Since future versions are not ruled out, this construct is provided ! 1024: as a means to allow the possibility of automatic version recognition, should ! 1025: it become necessary. ! 1026: Processors may signal an error if they receive documents labeled with ! 1027: versions they do not support. ! 1028: </p> ! 1029: <p>The function of the markup in an XML document is to describe its ! 1030: storage and logical structure and to associate attribute-value pairs ! 1031: with its logical structures. XML provides a mechanism, the <termref ! 1032: def="dt-doctype">document type declaration</termref>, to define ! 1033: constraints on the logical structure and to support the use of ! 1034: predefined storage units. ! 1035: ! 1036: <termdef id="dt-valid" term="Validity">An XML document is ! 1037: <term>valid</term> if it has an associated document type ! 1038: declaration and if the document ! 1039: complies with the constraints expressed in it.</termdef></p> ! 1040: <p>The document type declaration must appear before ! 1041: the first <termref def="dt-element">element</termref> in the document. ! 1042: <scrap lang="ebnf" id='xmldoc'> ! 1043: <head>Prolog</head> ! 1044: <prodgroup pcw2="6" pcw4="17.5" pcw5="9"> ! 1045: <prod id='NT-prolog'><lhs>prolog</lhs> ! 1046: <rhs><nt def='NT-XMLDecl'>XMLDecl</nt>? ! 1047: <nt def='NT-Misc'>Misc</nt>* ! 1048: (<nt def='NT-doctypedecl'>doctypedecl</nt> ! 1049: <nt def='NT-Misc'>Misc</nt>*)?</rhs></prod> ! 1050: <prod id='NT-XMLDecl'><lhs>XMLDecl</lhs> ! 1051: <rhs>&xmlpio; ! 1052: <nt def='NT-VersionInfo'>VersionInfo</nt> ! 1053: <nt def='NT-EncodingDecl'>EncodingDecl</nt>? ! 1054: <nt def='NT-SDDecl'>SDDecl</nt>? ! 1055: <nt def="NT-S">S</nt>? ! 1056: &pic;</rhs> ! 1057: </prod> ! 1058: <prod id='NT-VersionInfo'><lhs>VersionInfo</lhs> ! 1059: <rhs><nt def="NT-S">S</nt> 'version' <nt def='NT-Eq'>Eq</nt> ! 1060: (' <nt def="NT-VersionNum">VersionNum</nt> ' ! 1061: | " <nt def="NT-VersionNum">VersionNum</nt> ")</rhs> ! 1062: </prod> ! 1063: <prod id='NT-Eq'><lhs>Eq</lhs> ! 1064: <rhs><nt def='NT-S'>S</nt>? '=' <nt def='NT-S'>S</nt>?</rhs></prod> ! 1065: <prod id="NT-VersionNum"> ! 1066: <lhs>VersionNum</lhs> ! 1067: <rhs>([a-zA-Z0-9_.:] | '-')+</rhs> ! 1068: </prod> ! 1069: <prod id='NT-Misc'><lhs>Misc</lhs> ! 1070: <rhs><nt def='NT-Comment'>Comment</nt> | <nt def='NT-PI'>PI</nt> | ! 1071: <nt def='NT-S'>S</nt></rhs></prod> ! 1072: </prodgroup> ! 1073: </scrap></p> ! 1074: ! 1075: <p><termdef id="dt-doctype" term="Document Type Declaration">The XML ! 1076: <term>document type declaration</term> ! 1077: contains or points to ! 1078: <termref def='dt-markupdecl'>markup declarations</termref> ! 1079: that provide a grammar for a ! 1080: class of documents. ! 1081: This grammar is known as a document type definition, ! 1082: or <term>DTD</term>. ! 1083: The document type declaration can point to an external subset (a ! 1084: special kind of ! 1085: <termref def='dt-extent'>external entity</termref>) containing markup ! 1086: declarations, or can ! 1087: contain the markup declarations directly in an internal subset, or can do ! 1088: both. ! 1089: The DTD for a document consists of both subsets taken ! 1090: together.</termdef> ! 1091: </p> ! 1092: <p><termdef id="dt-markupdecl" term="markup declaration"> ! 1093: A <term>markup declaration</term> is ! 1094: an <termref def="dt-eldecl">element type declaration</termref>, ! 1095: an <termref def="dt-attdecl">attribute-list declaration</termref>, ! 1096: an <termref def="dt-entdecl">entity declaration</termref>, or ! 1097: a <termref def="dt-notdecl">notation declaration</termref>. ! 1098: </termdef> ! 1099: These declarations may be contained in whole or in part ! 1100: within <termref def='dt-PE'>parameter entities</termref>, ! 1101: as described in the well-formedness and validity constraints below. ! 1102: For fuller information, see ! 1103: <specref ref="sec-physical-struct"/>.</p> ! 1104: <scrap lang="ebnf" id='dtd'> ! 1105: <head>Document Type Definition</head> ! 1106: <prodgroup pcw2="6" pcw4="17.5" pcw5="9"> ! 1107: <prod id='NT-doctypedecl'><lhs>doctypedecl</lhs> ! 1108: <rhs>'<!DOCTYPE' <nt def='NT-S'>S</nt> ! 1109: <nt def='NT-Name'>Name</nt> (<nt def='NT-S'>S</nt> ! 1110: <nt def='NT-ExternalID'>ExternalID</nt>)? ! 1111: <nt def='NT-S'>S</nt>? ('[' ! 1112: (<nt def='NT-markupdecl'>markupdecl</nt> ! 1113: | <nt def='NT-PEReference'>PEReference</nt> ! 1114: | <nt def='NT-S'>S</nt>)* ! 1115: ']' ! 1116: <nt def='NT-S'>S</nt>?)? '>'</rhs> ! 1117: <vc def="vc-roottype"/> ! 1118: </prod> ! 1119: <prod id='NT-markupdecl'><lhs>markupdecl</lhs> ! 1120: <rhs><nt def='NT-elementdecl'>elementdecl</nt> ! 1121: | <nt def='NT-AttlistDecl'>AttlistDecl</nt> ! 1122: | <nt def='NT-EntityDecl'>EntityDecl</nt> ! 1123: | <nt def='NT-NotationDecl'>NotationDecl</nt> ! 1124: | <nt def='NT-PI'>PI</nt> ! 1125: | <nt def='NT-Comment'>Comment</nt> ! 1126: </rhs> ! 1127: <vc def='vc-PEinMarkupDecl'/> ! 1128: <wfc def="wfc-PEinInternalSubset"/> ! 1129: </prod> ! 1130: ! 1131: </prodgroup> ! 1132: </scrap> ! 1133: ! 1134: <p>The markup declarations may be made up in whole or in part of ! 1135: the <termref def='dt-repltext'>replacement text</termref> of ! 1136: <termref def='dt-PE'>parameter entities</termref>. ! 1137: The productions later in this specification for ! 1138: individual nonterminals (<nt def='NT-elementdecl'>elementdecl</nt>, ! 1139: <nt def='NT-AttlistDecl'>AttlistDecl</nt>, and so on) describe ! 1140: the declarations <emph>after</emph> all the parameter entities have been ! 1141: <termref def='dt-include'>included</termref>.</p> ! 1142: ! 1143: <vcnote id="vc-roottype"> ! 1144: <head>Root Element Type</head> ! 1145: <p> ! 1146: The <nt def='NT-Name'>Name</nt> in the document type declaration must ! 1147: match the element type of the <termref def='dt-root'>root element</termref>. ! 1148: </p> ! 1149: </vcnote> ! 1150: ! 1151: <vcnote id='vc-PEinMarkupDecl'> ! 1152: <head>Proper Declaration/PE Nesting</head> ! 1153: <p>Parameter-entity ! 1154: <termref def='dt-repltext'>replacement text</termref> must be properly nested ! 1155: with markup declarations. ! 1156: That is to say, if either the first character ! 1157: or the last character of a markup ! 1158: declaration (<nt def='NT-markupdecl'>markupdecl</nt> above) ! 1159: is contained in the replacement text for a ! 1160: <termref def='dt-PERef'>parameter-entity reference</termref>, ! 1161: both must be contained in the same replacement text.</p> ! 1162: </vcnote> ! 1163: <wfcnote id="wfc-PEinInternalSubset"> ! 1164: <head>PEs in Internal Subset</head> ! 1165: <p>In the internal DTD subset, ! 1166: <termref def='dt-PERef'>parameter-entity references</termref> ! 1167: can occur only where markup declarations can occur, not ! 1168: within markup declarations. (This does not apply to ! 1169: references that occur in ! 1170: external parameter entities or to the external subset.) ! 1171: </p> ! 1172: </wfcnote> ! 1173: <p> ! 1174: Like the internal subset, the external subset and ! 1175: any external parameter entities referred to in the DTD ! 1176: must consist of a series of complete markup declarations of the types ! 1177: allowed by the non-terminal symbol ! 1178: <nt def="NT-markupdecl">markupdecl</nt>, interspersed with white space ! 1179: or <termref def="dt-PERef">parameter-entity references</termref>. ! 1180: However, portions of the contents ! 1181: of the ! 1182: external subset or of external parameter entities may conditionally be ignored ! 1183: by using ! 1184: the <termref def="dt-cond-section">conditional section</termref> ! 1185: construct; this is not allowed in the internal subset. ! 1186: ! 1187: <scrap id="ext-Subset"> ! 1188: <head>External Subset</head> ! 1189: <prodgroup pcw2="6" pcw4="17.5" pcw5="9"> ! 1190: <prod id='NT-extSubset'><lhs>extSubset</lhs> ! 1191: <rhs><nt def='NT-TextDecl'>TextDecl</nt>? ! 1192: <nt def='NT-extSubsetDecl'>extSubsetDecl</nt></rhs></prod> ! 1193: <prod id='NT-extSubsetDecl'><lhs>extSubsetDecl</lhs> ! 1194: <rhs>( ! 1195: <nt def='NT-markupdecl'>markupdecl</nt> ! 1196: | <nt def='NT-conditionalSect'>conditionalSect</nt> ! 1197: | <nt def='NT-PEReference'>PEReference</nt> ! 1198: | <nt def='NT-S'>S</nt> ! 1199: )*</rhs> ! 1200: </prod> ! 1201: </prodgroup> ! 1202: </scrap></p> ! 1203: <p>The external subset and external parameter entities also differ ! 1204: from the internal subset in that in them, ! 1205: <termref def="dt-PERef">parameter-entity references</termref> ! 1206: are permitted <emph>within</emph> markup declarations, ! 1207: not only <emph>between</emph> markup declarations.</p> ! 1208: <p>An example of an XML document with a document type declaration: ! 1209: <eg><![CDATA[<?xml version="1.0"?> ! 1210: <!DOCTYPE greeting SYSTEM "hello.dtd"> ! 1211: <greeting>Hello, world!</greeting> ! 1212: ]]></eg> ! 1213: The <termref def="dt-sysid">system identifier</termref> ! 1214: "<code>hello.dtd</code>" gives the URI of a DTD for the document.</p> ! 1215: <p>The declarations can also be given locally, as in this ! 1216: example: ! 1217: <eg><![CDATA[<?xml version="1.0" encoding="UTF-8" ?> ! 1218: <!DOCTYPE greeting [ ! 1219: <!ELEMENT greeting (#PCDATA)> ! 1220: ]> ! 1221: <greeting>Hello, world!</greeting> ! 1222: ]]></eg> ! 1223: If both the external and internal subsets are used, the ! 1224: internal subset is considered to occur before the external subset. ! 1225: <!-- 'is considered to'? boo. whazzat mean? --> ! 1226: This has the effect that entity and attribute-list declarations in the ! 1227: internal subset take precedence over those in the external subset. ! 1228: </p> ! 1229: </div2> ! 1230: ! 1231: <div2 id='sec-rmd'> ! 1232: <head>Standalone Document Declaration</head> ! 1233: <p>Markup declarations can affect the content of the document, ! 1234: as passed from an <termref def="dt-xml-proc">XML processor</termref> ! 1235: to an application; examples are attribute defaults and entity ! 1236: declarations. ! 1237: The standalone document declaration, ! 1238: which may appear as a component of the XML declaration, signals ! 1239: whether or not there are such declarations which appear external to ! 1240: the <termref def='dt-docent'>document entity</termref>. ! 1241: <scrap lang="ebnf" id='fulldtd'> ! 1242: <head>Standalone Document Declaration</head> ! 1243: <prodgroup pcw2="4" pcw4="19.5" pcw5="9"> ! 1244: <prod id='NT-SDDecl'><lhs>SDDecl</lhs> ! 1245: <rhs> ! 1246: <nt def="NT-S">S</nt> ! 1247: 'standalone' <nt def='NT-Eq'>Eq</nt> ! 1248: (("'" ('yes' | 'no') "'") | ('"' ('yes' | 'no') '"')) ! 1249: </rhs> ! 1250: <vc def='vc-check-rmd'/></prod> ! 1251: </prodgroup> ! 1252: </scrap></p> ! 1253: <p> ! 1254: In a standalone document declaration, the value "<code>yes</code>" indicates ! 1255: that there ! 1256: are no markup declarations external to the <termref def='dt-docent'>document ! 1257: entity</termref> (either in the DTD external subset, or in an ! 1258: external parameter entity referenced from the internal subset) ! 1259: which affect the information passed from the XML processor to ! 1260: the application. ! 1261: The value "<code>no</code>" indicates that there are or may be such ! 1262: external markup declarations. ! 1263: Note that the standalone document declaration only ! 1264: denotes the presence of external <emph>declarations</emph>; the presence, in a ! 1265: document, of ! 1266: references to external <emph>entities</emph>, when those entities are ! 1267: internally declared, ! 1268: does not change its standalone status.</p> ! 1269: <p>If there are no external markup declarations, the standalone document ! 1270: declaration has no meaning. ! 1271: If there are external markup declarations but there is no standalone ! 1272: document declaration, the value "<code>no</code>" is assumed.</p> ! 1273: <p>Any XML document for which <code>standalone="no"</code> holds can ! 1274: be converted algorithmically to a standalone document, ! 1275: which may be desirable for some network delivery applications.</p> ! 1276: <vcnote id='vc-check-rmd'> ! 1277: <head>Standalone Document Declaration</head> ! 1278: <p>The standalone document declaration must have ! 1279: the value "<code>no</code>" if any external markup declarations ! 1280: contain declarations of:</p><ulist> ! 1281: <item><p>attributes with <termref def="dt-default">default</termref> values, if ! 1282: elements to which ! 1283: these attributes apply appear in the document without ! 1284: specifications of values for these attributes, or</p></item> ! 1285: <item><p>entities (other than &magicents;), ! 1286: if <termref def="dt-entref">references</termref> to those ! 1287: entities appear in the document, or</p> ! 1288: </item> ! 1289: <item><p>attributes with values subject to ! 1290: <titleref href='AVNormalize'>normalization</titleref>, where the ! 1291: attribute appears in the document with a value which will ! 1292: change as a result of normalization, or</p> ! 1293: </item> ! 1294: <item> ! 1295: <p>element types with <termref def="dt-elemcontent">element content</termref>, ! 1296: if white space occurs ! 1297: directly within any instance of those types. ! 1298: </p></item> ! 1299: </ulist> ! 1300: ! 1301: </vcnote> ! 1302: <p>An example XML declaration with a standalone document declaration:<eg ! 1303: ><?xml version="&XML.version;" standalone='yes'?></eg></p> ! 1304: </div2> ! 1305: <div2 id='sec-white-space'> ! 1306: <head>White Space Handling</head> ! 1307: ! 1308: <p>In editing XML documents, it is often convenient to use "white space" ! 1309: (spaces, tabs, and blank lines, denoted by the nonterminal ! 1310: <nt def='NT-S'>S</nt> in this specification) to ! 1311: set apart the markup for greater readability. Such white space is typically ! 1312: not intended for inclusion in the delivered version of the document. ! 1313: On the other hand, "significant" white space that should be preserved in the ! 1314: delivered version is common, for example in poetry and ! 1315: source code.</p> ! 1316: <p>An <termref def='dt-xml-proc'>XML processor</termref> ! 1317: must always pass all characters in a document that are not ! 1318: markup through to the application. A <termref def='dt-validating'> ! 1319: validating XML processor</termref> must also inform the application ! 1320: which of these characters constitute white space appearing ! 1321: in <termref def="dt-elemcontent">element content</termref>. ! 1322: </p> ! 1323: <p>A special <termref def='dt-attr'>attribute</termref> ! 1324: named <kw>xml:space</kw> may be attached to an element ! 1325: to signal an intention that in that element, ! 1326: white space should be preserved by applications. ! 1327: In valid documents, this attribute, like any other, must be ! 1328: <termref def="dt-attdecl">declared</termref> if it is used. ! 1329: When declared, it must be given as an ! 1330: <termref def='dt-enumerated'>enumerated type</termref> whose only ! 1331: possible values are "<code>default</code>" and "<code>preserve</code>". ! 1332: For example:<eg><![CDATA[ <!ATTLIST poem xml:space (default|preserve) 'preserve'>]]></eg></p> ! 1333: <p>The value "<code>default</code>" signals that applications' ! 1334: default white-space processing modes are acceptable for this element; the ! 1335: value "<code>preserve</code>" indicates the intent that applications preserve ! 1336: all the white space. ! 1337: This declared intent is considered to apply to all elements within the content ! 1338: of the element where it is specified, unless overriden with another instance ! 1339: of the <kw>xml:space</kw> attribute. ! 1340: </p> ! 1341: <p>The <termref def='dt-root'>root element</termref> of any document ! 1342: is considered to have signaled no intentions as regards application space ! 1343: handling, unless it provides a value for ! 1344: this attribute or the attribute is declared with a default value. ! 1345: </p> ! 1346: ! 1347: </div2> ! 1348: <div2 id='sec-line-ends'> ! 1349: <head>End-of-Line Handling</head> ! 1350: <p>XML <termref def='dt-parsedent'>parsed entities</termref> are often stored in ! 1351: computer files which, for editing convenience, are organized into lines. ! 1352: These lines are typically separated by some combination of the characters ! 1353: carriage-return (#xD) and line-feed (#xA).</p> ! 1354: <p>To simplify the tasks of <termref def='dt-app'>applications</termref>, ! 1355: wherever an external parsed entity or the literal entity value ! 1356: of an internal parsed entity contains either the literal ! 1357: two-character sequence "#xD#xA" or a standalone literal ! 1358: #xD, an <termref def='dt-xml-proc'>XML processor</termref> must ! 1359: pass to the application the single character #xA. ! 1360: (This behavior can ! 1361: conveniently be produced by normalizing all ! 1362: line breaks to #xA on input, before parsing.) ! 1363: </p> ! 1364: </div2> ! 1365: <div2 id='sec-lang-tag'> ! 1366: <head>Language Identification</head> ! 1367: <p>In document processing, it is often useful to ! 1368: identify the natural or formal language ! 1369: in which the content is ! 1370: written. ! 1371: A special <termref def="dt-attr">attribute</termref> named ! 1372: <kw>xml:lang</kw> may be inserted in ! 1373: documents to specify the ! 1374: language used in the contents and attribute values ! 1375: of any element in an XML document. ! 1376: In valid documents, this attribute, like any other, must be ! 1377: <termref def="dt-attdecl">declared</termref> if it is used. ! 1378: The values of the attribute are language identifiers as defined ! 1379: by <bibref ref="RFC1766"/>, "Tags for the Identification of Languages": ! 1380: <scrap lang='ebnf'> ! 1381: <head>Language Identification</head> ! 1382: <prod id='NT-LanguageID'><lhs>LanguageID</lhs> ! 1383: <rhs><nt def='NT-Langcode'>Langcode</nt> ! 1384: ('-' <nt def='NT-Subcode'>Subcode</nt>)*</rhs></prod> ! 1385: <prod id='NT-Langcode'><lhs>Langcode</lhs> ! 1386: <rhs><nt def='NT-ISO639Code'>ISO639Code</nt> | ! 1387: <nt def='NT-IanaCode'>IanaCode</nt> | ! 1388: <nt def='NT-UserCode'>UserCode</nt></rhs> ! 1389: </prod> ! 1390: <prod id='NT-ISO639Code'><lhs>ISO639Code</lhs> ! 1391: <rhs>([a-z] | [A-Z]) ([a-z] | [A-Z])</rhs></prod> ! 1392: <prod id='NT-IanaCode'><lhs>IanaCode</lhs> ! 1393: <rhs>('i' | 'I') '-' ([a-z] | [A-Z])+</rhs></prod> ! 1394: <prod id='NT-UserCode'><lhs>UserCode</lhs> ! 1395: <rhs>('x' | 'X') '-' ([a-z] | [A-Z])+</rhs></prod> ! 1396: <prod id='NT-Subcode'><lhs>Subcode</lhs> ! 1397: <rhs>([a-z] | [A-Z])+</rhs></prod> ! 1398: </scrap> ! 1399: The <nt def='NT-Langcode'>Langcode</nt> may be any of the following: ! 1400: <ulist> ! 1401: <item><p>a two-letter language code as defined by ! 1402: <bibref ref="ISO639"/>, "Codes ! 1403: for the representation of names of languages"</p></item> ! 1404: <item><p>a language identifier registered with the Internet ! 1405: Assigned Numbers Authority <bibref ref='IANA'/>; these begin with the ! 1406: prefix "<code>i-</code>" (or "<code>I-</code>")</p></item> ! 1407: <item><p>a language identifier assigned by the user, or agreed on ! 1408: between parties in private use; these must begin with the ! 1409: prefix "<code>x-</code>" or "<code>X-</code>" in order to ensure that they do not conflict ! 1410: with names later standardized or registered with IANA</p></item> ! 1411: </ulist></p> ! 1412: <p>There may be any number of <nt def='NT-Subcode'>Subcode</nt> segments; if ! 1413: the first ! 1414: subcode segment exists and the Subcode consists of two ! 1415: letters, then it must be a country code from ! 1416: <bibref ref="ISO3166"/>, "Codes ! 1417: for the representation of names of countries." ! 1418: If the first ! 1419: subcode consists of more than two letters, it must be ! 1420: a subcode for the language in question registered with IANA, ! 1421: unless the <nt def='NT-Langcode'>Langcode</nt> begins with the prefix ! 1422: "<code>x-</code>" or ! 1423: "<code>X-</code>". </p> ! 1424: <p>It is customary to give the language code in lower case, and ! 1425: the country code (if any) in upper case. ! 1426: Note that these values, unlike other names in XML documents, ! 1427: are case insensitive.</p> ! 1428: <p>For example: ! 1429: <eg><![CDATA[<p xml:lang="en">The quick brown fox jumps over the lazy dog.</p> ! 1430: <p xml:lang="en-GB">What colour is it?</p> ! 1431: <p xml:lang="en-US">What color is it?</p> ! 1432: <sp who="Faust" desc='leise' xml:lang="de"> ! 1433: <l>Habe nun, ach! Philosophie,</l> ! 1434: <l>Juristerei, und Medizin</l> ! 1435: <l>und leider auch Theologie</l> ! 1436: <l>durchaus studiert mit heißem Bemüh'n.</l> ! 1437: </sp>]]></eg></p> ! 1438: <!--<p>The xml:lang value is considered to apply both to the contents of an ! 1439: element and ! 1440: (unless otherwise via attribute default values) to the ! 1441: values of all of its attributes with free-text (CDATA) values. --> ! 1442: <p>The intent declared with <kw>xml:lang</kw> is considered to apply to ! 1443: all attributes and content of the element where it is specified, ! 1444: unless overridden with an instance of <kw>xml:lang</kw> ! 1445: on another element within that content.</p> ! 1446: <!-- ! 1447: If no ! 1448: value is specified for xml:lang on an element, and no default value is ! 1449: defined for it in the DTD, then the xml:lang attribute of any element ! 1450: takes the same value it has in the parent element, if any. The two ! 1451: technical terms in the following example both have the same effective ! 1452: value for xml:lang: ! 1453: ! 1454: <p xml:lang="en">Here the keywords are ! 1455: <term xml:lang="en">shift</term> and ! 1456: <term>reduce</term>. ...</p> ! 1457: ! 1458: The application, not the XML processor, is responsible for this ' ! 1459: inheritance' of attribute values. ! 1460: --> ! 1461: <p>A simple declaration for <kw>xml:lang</kw> might take ! 1462: the form ! 1463: <eg>xml:lang NMTOKEN #IMPLIED</eg> ! 1464: but specific default values may also be given, if appropriate. In a ! 1465: collection of French poems for English students, with glosses and ! 1466: notes in English, the xml:lang attribute might be declared this way: ! 1467: <eg><![CDATA[ <!ATTLIST poem xml:lang NMTOKEN 'fr'> ! 1468: <!ATTLIST gloss xml:lang NMTOKEN 'en'> ! 1469: <!ATTLIST note xml:lang NMTOKEN 'en'>]]></eg> ! 1470: </p> ! 1471: ! 1472: </div2> ! 1473: </div1> ! 1474: <!-- &Elements; --> ! 1475: ! 1476: <div1 id='sec-logical-struct'> ! 1477: <head>Logical Structures</head> ! 1478: ! 1479: <p><termdef id="dt-element" term="Element">Each <termref ! 1480: def="dt-xml-doc">XML document</termref> contains one or more ! 1481: <term>elements</term>, the boundaries of which are ! 1482: either delimited by <termref def="dt-stag">start-tags</termref> ! 1483: and <termref def="dt-etag">end-tags</termref>, or, for <termref ! 1484: def="dt-empty">empty</termref> elements, by an <termref ! 1485: def="dt-eetag">empty-element tag</termref>. Each element has a type, ! 1486: identified by name, sometimes called its "generic ! 1487: identifier" (GI), and may have a set of ! 1488: attribute specifications.</termdef> Each attribute specification ! 1489: has a <termref ! 1490: def="dt-attrname">name</termref> and a <termref ! 1491: def="dt-attrval">value</termref>. ! 1492: </p> ! 1493: <scrap lang='ebnf'><head>Element</head> ! 1494: <prod id='NT-element'><lhs>element</lhs> ! 1495: <rhs><nt def='NT-EmptyElemTag'>EmptyElemTag</nt></rhs> ! 1496: <rhs>| <nt def='NT-STag'>STag</nt> <nt def='NT-content'>content</nt> ! 1497: <nt def='NT-ETag'>ETag</nt></rhs> ! 1498: <wfc def='GIMatch'/> ! 1499: <vc def='elementvalid'/> ! 1500: </prod> ! 1501: </scrap> ! 1502: <p>This specification does not constrain the semantics, use, or (beyond ! 1503: syntax) names of the element types and attributes, except that names ! 1504: beginning with a match to <code>(('X'|'x')('M'|'m')('L'|'l'))</code> ! 1505: are reserved for standardization in this or future versions of this ! 1506: specification. ! 1507: </p> ! 1508: <wfcnote id='GIMatch'> ! 1509: <head>Element Type Match</head> ! 1510: <p> ! 1511: The <nt def='NT-Name'>Name</nt> in an element's end-tag must match ! 1512: the element type in ! 1513: the start-tag. ! 1514: </p> ! 1515: </wfcnote> ! 1516: <vcnote id='elementvalid'> ! 1517: <head>Element Valid</head> ! 1518: <p>An element is ! 1519: valid if ! 1520: there is a declaration matching ! 1521: <nt def='NT-elementdecl'>elementdecl</nt> where the ! 1522: <nt def='NT-Name'>Name</nt> matches the element type, and ! 1523: one of the following holds:</p> ! 1524: <olist> ! 1525: <item><p>The declaration matches <kw>EMPTY</kw> and the element has no ! 1526: <termref def='dt-content'>content</termref>.</p></item> ! 1527: <item><p>The declaration matches <nt def='NT-children'>children</nt> and ! 1528: the sequence of ! 1529: <termref def="dt-parentchild">child elements</termref> ! 1530: belongs to the language generated by the regular expression in ! 1531: the content model, with optional white space (characters ! 1532: matching the nonterminal <nt def='NT-S'>S</nt>) between each pair ! 1533: of child elements.</p></item> ! 1534: <item><p>The declaration matches <nt def='NT-Mixed'>Mixed</nt> and ! 1535: the content consists of <termref def='dt-chardata'>character ! 1536: data</termref> and <termref def='dt-parentchild'>child elements</termref> ! 1537: whose types match names in the content model.</p></item> ! 1538: <item><p>The declaration matches <kw>ANY</kw>, and the types ! 1539: of any <termref def='dt-parentchild'>child elements</termref> have ! 1540: been declared.</p></item> ! 1541: </olist> ! 1542: </vcnote> ! 1543: ! 1544: <div2 id='sec-starttags'> ! 1545: <head>Start-Tags, End-Tags, and Empty-Element Tags</head> ! 1546: ! 1547: <p><termdef id="dt-stag" term="Start-Tag">The beginning of every ! 1548: non-empty XML element is marked by a <term>start-tag</term>. ! 1549: <scrap lang='ebnf'> ! 1550: <head>Start-tag</head> ! 1551: <prodgroup pcw2="6" pcw4="15" pcw5="11.5"> ! 1552: <prod id='NT-STag'><lhs>STag</lhs> ! 1553: <rhs>'<' <nt def='NT-Name'>Name</nt> ! 1554: (<nt def='NT-S'>S</nt> <nt def='NT-Attribute'>Attribute</nt>)* ! 1555: <nt def='NT-S'>S</nt>? '>'</rhs> ! 1556: <wfc def="uniqattspec"/> ! 1557: </prod> ! 1558: <prod id='NT-Attribute'><lhs>Attribute</lhs> ! 1559: <rhs><nt def='NT-Name'>Name</nt> <nt def='NT-Eq'>Eq</nt> ! 1560: <nt def='NT-AttValue'>AttValue</nt></rhs> ! 1561: <vc def='ValueType'/> ! 1562: <wfc def='NoExternalRefs'/> ! 1563: <wfc def='CleanAttrVals'/></prod> ! 1564: </prodgroup> ! 1565: </scrap> ! 1566: The <nt def='NT-Name'>Name</nt> in ! 1567: the start- and end-tags gives the ! 1568: element's <term>type</term>.</termdef> ! 1569: <termdef id="dt-attr" term="Attribute"> ! 1570: The <nt def='NT-Name'>Name</nt>-<nt def='NT-AttValue'>AttValue</nt> pairs are ! 1571: referred to as ! 1572: the <term>attribute specifications</term> of the element</termdef>, ! 1573: <termdef id="dt-attrname" term="Attribute Name">with the ! 1574: <nt def='NT-Name'>Name</nt> in each pair ! 1575: referred to as the <term>attribute name</term></termdef> and ! 1576: <termdef id="dt-attrval" term="Attribute Value">the content of the ! 1577: <nt def='NT-AttValue'>AttValue</nt> (the text between the ! 1578: <code>'</code> or <code>"</code> delimiters) ! 1579: as the <term>attribute value</term>.</termdef> ! 1580: </p> ! 1581: <wfcnote id='uniqattspec'> ! 1582: <head>Unique Att Spec</head> ! 1583: <p> ! 1584: No attribute name may appear more than once in the same start-tag ! 1585: or empty-element tag. ! 1586: </p> ! 1587: </wfcnote> ! 1588: <vcnote id='ValueType'> ! 1589: <head>Attribute Value Type</head> ! 1590: <p> ! 1591: The attribute must have been declared; the value must be of the type ! 1592: declared for it. ! 1593: (For attribute types, see <specref ref='attdecls'/>.) ! 1594: </p> ! 1595: </vcnote> ! 1596: <wfcnote id='NoExternalRefs'> ! 1597: <head>No External Entity References</head> ! 1598: <p> ! 1599: Attribute values cannot contain direct or indirect entity references ! 1600: to external entities. ! 1601: </p> ! 1602: </wfcnote> ! 1603: <wfcnote id='CleanAttrVals'> ! 1604: <head>No <code><</code> in Attribute Values</head> ! 1605: <p>The <termref def='dt-repltext'>replacement text</termref> of any entity ! 1606: referred to directly or indirectly in an attribute ! 1607: value (other than "<code>&lt;</code>") must not contain ! 1608: a <code><</code>. ! 1609: </p></wfcnote> ! 1610: <p>An example of a start-tag: ! 1611: <eg><termdef id="dt-dog" term="dog"></eg></p> ! 1612: <p><termdef id="dt-etag" term="End Tag">The end of every element ! 1613: that begins with a start-tag must ! 1614: be marked by an <term>end-tag</term> ! 1615: containing a name that echoes the element's type as given in the ! 1616: start-tag: ! 1617: <scrap lang='ebnf'> ! 1618: <head>End-tag</head> ! 1619: <prodgroup pcw2="6" pcw4="15" pcw5="11.5"> ! 1620: <prod id='NT-ETag'><lhs>ETag</lhs> ! 1621: <rhs>'</' <nt def='NT-Name'>Name</nt> ! 1622: <nt def='NT-S'>S</nt>? '>'</rhs></prod> ! 1623: </prodgroup> ! 1624: </scrap> ! 1625: </termdef></p> ! 1626: <p>An example of an end-tag:<eg></termdef></eg></p> ! 1627: <p><termdef id="dt-content" term="Content">The ! 1628: <termref def='dt-text'>text</termref> between the start-tag and ! 1629: end-tag is called the element's ! 1630: <term>content</term>: ! 1631: <scrap lang='ebnf'> ! 1632: <head>Content of Elements</head> ! 1633: <prodgroup pcw2="6" pcw4="15" pcw5="11.5"> ! 1634: <prod id='NT-content'><lhs>content</lhs> ! 1635: <rhs>(<nt def='NT-element'>element</nt> | <nt def='NT-CharData'>CharData</nt> ! 1636: | <nt def='NT-Reference'>Reference</nt> | <nt def='NT-CDSect'>CDSect</nt> ! 1637: | <nt def='NT-PI'>PI</nt> | <nt def='NT-Comment'>Comment</nt>)*</rhs> ! 1638: </prod> ! 1639: </prodgroup> ! 1640: </scrap> ! 1641: </termdef></p> ! 1642: <p><termdef id="dt-empty" term="Empty">If an element is <term>empty</term>, ! 1643: it must be represented either by a start-tag immediately followed ! 1644: by an end-tag or by an empty-element tag.</termdef> ! 1645: <termdef id="dt-eetag" term="empty-element tag">An ! 1646: <term>empty-element tag</term> takes a special form: ! 1647: <scrap lang='ebnf'> ! 1648: <head>Tags for Empty Elements</head> ! 1649: <prodgroup pcw2="6" pcw4="15" pcw5="11.5"> ! 1650: <prod id='NT-EmptyElemTag'><lhs>EmptyElemTag</lhs> ! 1651: <rhs>'<' <nt def='NT-Name'>Name</nt> (<nt def='NT-S'>S</nt> ! 1652: <nt def='NT-Attribute'>Attribute</nt>)* <nt def='NT-S'>S</nt>? ! 1653: '/>'</rhs> ! 1654: <wfc def="uniqattspec"/> ! 1655: </prod> ! 1656: </prodgroup> ! 1657: </scrap> ! 1658: </termdef></p> ! 1659: <p>Empty-element tags may be used for any element which has no ! 1660: content, whether or not it is declared using the keyword ! 1661: <kw>EMPTY</kw>. ! 1662: <termref def='dt-interop'>For interoperability</termref>, the empty-element ! 1663: tag must be used, and can only be used, for elements which are ! 1664: <termref def='dt-eldecl'>declared</termref> <kw>EMPTY</kw>.</p> ! 1665: <p>Examples of empty elements: ! 1666: <eg><IMG align="left" ! 1667: src="http://www.w3.org/Icons/WWW/w3c_home" /> ! 1668: <br></br> ! 1669: <br/></eg></p> ! 1670: </div2> ! 1671: ! 1672: <div2 id='elemdecls'> ! 1673: <head>Element Type Declarations</head> ! 1674: ! 1675: <p>The <termref def="dt-element">element</termref> structure of an ! 1676: <termref def="dt-xml-doc">XML document</termref> may, for ! 1677: <termref def="dt-valid">validation</termref> purposes, ! 1678: be constrained ! 1679: using element type and attribute-list declarations. ! 1680: An element type declaration constrains the element's ! 1681: <termref def="dt-content">content</termref>. ! 1682: </p> ! 1683: ! 1684: <p>Element type declarations often constrain which element types can ! 1685: appear as <termref def="dt-parentchild">children</termref> of the element. ! 1686: At user option, an XML processor may issue a warning ! 1687: when a declaration mentions an element type for which no declaration ! 1688: is provided, but this is not an error.</p> ! 1689: <p><termdef id="dt-eldecl" term="Element Type declaration">An <term>element ! 1690: type declaration</term> takes the form: ! 1691: <scrap lang='ebnf'> ! 1692: <head>Element Type Declaration</head> ! 1693: <prodgroup pcw2="5.5" pcw4="18" pcw5="9"> ! 1694: <prod id='NT-elementdecl'><lhs>elementdecl</lhs> ! 1695: <rhs>'<!ELEMENT' <nt def='NT-S'>S</nt> ! 1696: <nt def='NT-Name'>Name</nt> ! 1697: <nt def='NT-S'>S</nt> ! 1698: <nt def='NT-contentspec'>contentspec</nt> ! 1699: <nt def='NT-S'>S</nt>? '>'</rhs> ! 1700: <vc def='EDUnique'/></prod> ! 1701: <prod id='NT-contentspec'><lhs>contentspec</lhs> ! 1702: <rhs>'EMPTY' ! 1703: | 'ANY' ! 1704: | <nt def='NT-Mixed'>Mixed</nt> ! 1705: | <nt def='NT-children'>children</nt> ! 1706: </rhs> ! 1707: </prod> ! 1708: </prodgroup> ! 1709: </scrap> ! 1710: where the <nt def='NT-Name'>Name</nt> gives the element type ! 1711: being declared.</termdef> ! 1712: </p> ! 1713: ! 1714: <vcnote id='EDUnique'> ! 1715: <head>Unique Element Type Declaration</head> ! 1716: <p> ! 1717: No element type may be declared more than once. ! 1718: </p> ! 1719: </vcnote> ! 1720: ! 1721: <p>Examples of element type declarations: ! 1722: <eg><!ELEMENT br EMPTY> ! 1723: <!ELEMENT p (#PCDATA|emph)* > ! 1724: <!ELEMENT %name.para; %content.para; > ! 1725: <!ELEMENT container ANY></eg></p> ! 1726: ! 1727: <div3 id='sec-element-content'> ! 1728: <head>Element Content</head> ! 1729: ! 1730: <p><termdef id='dt-elemcontent' term='Element content'>An element <termref ! 1731: def="dt-stag">type</termref> has ! 1732: <term>element content</term> when elements of that ! 1733: type must contain only <termref def='dt-parentchild'>child</termref> ! 1734: elements (no character data), optionally separated by ! 1735: white space (characters matching the nonterminal ! 1736: <nt def='NT-S'>S</nt>). ! 1737: </termdef> ! 1738: In this case, the ! 1739: constraint includes a content model, a simple grammar governing ! 1740: the allowed types of the child ! 1741: elements and the order in which they are allowed to appear. ! 1742: The grammar is built on ! 1743: content particles (<nt def='NT-cp'>cp</nt>s), which consist of names, ! 1744: choice lists of content particles, or ! 1745: sequence lists of content particles: ! 1746: <scrap lang='ebnf'> ! 1747: <head>Element-content Models</head> ! 1748: <prodgroup pcw2="5.5" pcw4="16" pcw5="11"> ! 1749: <prod id='NT-children'><lhs>children</lhs> ! 1750: <rhs>(<nt def='NT-choice'>choice</nt> ! 1751: | <nt def='NT-seq'>seq</nt>) ! 1752: ('?' | '*' | '+')?</rhs></prod> ! 1753: <prod id='NT-cp'><lhs>cp</lhs> ! 1754: <rhs>(<nt def='NT-Name'>Name</nt> ! 1755: | <nt def='NT-choice'>choice</nt> ! 1756: | <nt def='NT-seq'>seq</nt>) ! 1757: ('?' | '*' | '+')?</rhs></prod> ! 1758: <prod id='NT-choice'><lhs>choice</lhs> ! 1759: <rhs>'(' <nt def='NT-S'>S</nt>? cp ! 1760: ( <nt def='NT-S'>S</nt>? '|' <nt def='NT-S'>S</nt>? <nt def='NT-cp'>cp</nt> )* ! 1761: <nt def='NT-S'>S</nt>? ')'</rhs> ! 1762: <vc def='vc-PEinGroup'/></prod> ! 1763: <prod id='NT-seq'><lhs>seq</lhs> ! 1764: <rhs>'(' <nt def='NT-S'>S</nt>? cp ! 1765: ( <nt def='NT-S'>S</nt>? ',' <nt def='NT-S'>S</nt>? <nt def='NT-cp'>cp</nt> )* ! 1766: <nt def='NT-S'>S</nt>? ')'</rhs> ! 1767: <vc def='vc-PEinGroup'/></prod> ! 1768: ! 1769: </prodgroup> ! 1770: </scrap> ! 1771: where each <nt def='NT-Name'>Name</nt> is the type of an element which may ! 1772: appear as a <termref def="dt-parentchild">child</termref>. ! 1773: Any content ! 1774: particle in a choice list may appear in the <termref ! 1775: def="dt-elemcontent">element content</termref> at the location where ! 1776: the choice list appears in the grammar; ! 1777: content particles occurring in a sequence list must each ! 1778: appear in the <termref def="dt-elemcontent">element content</termref> in the ! 1779: order given in the list. ! 1780: The optional character following a name or list governs ! 1781: whether the element or the content particles in the list may occur one ! 1782: or more (<code>+</code>), zero or more (<code>*</code>), or zero or ! 1783: one times (<code>?</code>). ! 1784: The absence of such an operator means that the element or content particle ! 1785: must appear exactly once. ! 1786: This syntax ! 1787: and meaning are identical to those used in the productions in this ! 1788: specification.</p> ! 1789: <p> ! 1790: The content of an element matches a content model if and only if it is ! 1791: possible to trace out a path through the content model, obeying the ! 1792: sequence, choice, and repetition operators and matching each element in ! 1793: the content against an element type in the content model. <termref ! 1794: def='dt-compat'>For compatibility</termref>, it is an error ! 1795: if an element in the document can ! 1796: match more than one occurrence of an element type in the content model. ! 1797: For more information, see <specref ref="determinism"/>. ! 1798: <!-- appendix <specref ref="determinism"/>. --> ! 1799: <!-- appendix on deterministic content models. --> ! 1800: </p> ! 1801: <vcnote id='vc-PEinGroup'> ! 1802: <head>Proper Group/PE Nesting</head> ! 1803: <p>Parameter-entity ! 1804: <termref def='dt-repltext'>replacement text</termref> must be properly nested ! 1805: with parenthetized groups. ! 1806: That is to say, if either of the opening or closing parentheses ! 1807: in a <nt def='NT-choice'>choice</nt>, <nt def='NT-seq'>seq</nt>, or ! 1808: <nt def='NT-Mixed'>Mixed</nt> construct ! 1809: is contained in the replacement text for a ! 1810: <termref def='dt-PERef'>parameter entity</termref>, ! 1811: both must be contained in the same replacement text.</p> ! 1812: <p><termref def='dt-interop'>For interoperability</termref>, ! 1813: if a parameter-entity reference appears in a ! 1814: <nt def='NT-choice'>choice</nt>, <nt def='NT-seq'>seq</nt>, or ! 1815: <nt def='NT-Mixed'>Mixed</nt> construct, its replacement text ! 1816: should not be empty, and ! 1817: neither the first nor last non-blank ! 1818: character of the replacement text should be a connector ! 1819: (<code>|</code> or <code>,</code>). ! 1820: </p> ! 1821: </vcnote> ! 1822: <p>Examples of element-content models: ! 1823: <eg><!ELEMENT spec (front, body, back?)> ! 1824: <!ELEMENT div1 (head, (p | list | note)*, div2*)> ! 1825: <!ELEMENT dictionary-body (%div.mix; | %dict.mix;)*></eg></p> ! 1826: </div3> ! 1827: ! 1828: <div3 id='sec-mixed-content'> ! 1829: <head>Mixed Content</head> ! 1830: ! 1831: <p><termdef id='dt-mixed' term='Mixed Content'>An element ! 1832: <termref def='dt-stag'>type</termref> has ! 1833: <term>mixed content</term> when elements of that type may contain ! 1834: character data, optionally interspersed with ! 1835: <termref def="dt-parentchild">child</termref> elements.</termdef> ! 1836: In this case, the types of the child elements ! 1837: may be constrained, but not their order or their number of occurrences: ! 1838: <scrap lang='ebnf'> ! 1839: <head>Mixed-content Declaration</head> ! 1840: <prodgroup pcw2="5.5" pcw4="16" pcw5="11"> ! 1841: <prod id='NT-Mixed'><lhs>Mixed</lhs> ! 1842: <rhs>'(' <nt def='NT-S'>S</nt>? ! 1843: '#PCDATA' ! 1844: (<nt def='NT-S'>S</nt>? ! 1845: '|' ! 1846: <nt def='NT-S'>S</nt>? ! 1847: <nt def='NT-Name'>Name</nt>)* ! 1848: <nt def='NT-S'>S</nt>? ! 1849: ')*' </rhs> ! 1850: <rhs>| '(' <nt def='NT-S'>S</nt>? '#PCDATA' <nt def='NT-S'>S</nt>? ')' ! 1851: </rhs><vc def='vc-PEinGroup'/> ! 1852: <vc def='vc-MixedChildrenUnique'/> ! 1853: </prod> ! 1854: ! 1855: </prodgroup> ! 1856: </scrap> ! 1857: where the <nt def='NT-Name'>Name</nt>s give the types of elements ! 1858: that may appear as children. ! 1859: </p> ! 1860: <vcnote id='vc-MixedChildrenUnique'> ! 1861: <head>No Duplicate Types</head> ! 1862: <p>The same name must not appear more than once in a single mixed-content ! 1863: declaration. ! 1864: </p></vcnote> ! 1865: <p>Examples of mixed content declarations: ! 1866: <eg><!ELEMENT p (#PCDATA|a|ul|b|i|em)*> ! 1867: <!ELEMENT p (#PCDATA | %font; | %phrase; | %special; | %form;)* > ! 1868: <!ELEMENT b (#PCDATA)></eg></p> ! 1869: </div3> ! 1870: </div2> ! 1871: ! 1872: <div2 id='attdecls'> ! 1873: <head>Attribute-List Declarations</head> ! 1874: ! 1875: <p><termref def="dt-attr">Attributes</termref> are used to associate ! 1876: name-value pairs with <termref def="dt-element">elements</termref>. ! 1877: Attribute specifications may appear only within <termref ! 1878: def="dt-stag">start-tags</termref> ! 1879: and <termref def="dt-eetag">empty-element tags</termref>; ! 1880: thus, the productions used to ! 1881: recognize them appear in <specref ref='sec-starttags'/>. ! 1882: Attribute-list ! 1883: declarations may be used: ! 1884: <ulist> ! 1885: <item><p>To define the set of attributes pertaining to a given ! 1886: element type.</p></item> ! 1887: <item><p>To establish type constraints for these ! 1888: attributes.</p></item> ! 1889: <item><p>To provide <termref def="dt-default">default values</termref> ! 1890: for attributes.</p></item> ! 1891: </ulist> ! 1892: </p> ! 1893: <p><termdef id="dt-attdecl" term="Attribute-List Declaration"> ! 1894: <term>Attribute-list declarations</term> specify the name, data type, and default ! 1895: value (if any) of each attribute associated with a given element type: ! 1896: <scrap lang='ebnf'> ! 1897: <head>Attribute-list Declaration</head> ! 1898: <prod id='NT-AttlistDecl'><lhs>AttlistDecl</lhs> ! 1899: <rhs>'<!ATTLIST' <nt def='NT-S'>S</nt> ! 1900: <nt def='NT-Name'>Name</nt> ! 1901: <nt def='NT-AttDef'>AttDef</nt>* ! 1902: <nt def='NT-S'>S</nt>? '>'</rhs> ! 1903: </prod> ! 1904: <prod id='NT-AttDef'><lhs>AttDef</lhs> ! 1905: <rhs><nt def='NT-S'>S</nt> <nt def='NT-Name'>Name</nt> ! 1906: <nt def='NT-S'>S</nt> <nt def='NT-AttType'>AttType</nt> ! 1907: <nt def='NT-S'>S</nt> <nt def='NT-DefaultDecl'>DefaultDecl</nt></rhs> ! 1908: </prod> ! 1909: </scrap> ! 1910: The <nt def="NT-Name">Name</nt> in the ! 1911: <nt def='NT-AttlistDecl'>AttlistDecl</nt> rule is the type of an element. At ! 1912: user option, an XML processor may issue a warning if attributes are ! 1913: declared for an element type not itself declared, but this is not an ! 1914: error. The <nt def='NT-Name'>Name</nt> in the ! 1915: <nt def='NT-AttDef'>AttDef</nt> rule is ! 1916: the name of the attribute.</termdef></p> ! 1917: <p> ! 1918: When more than one <nt def='NT-AttlistDecl'>AttlistDecl</nt> is provided for a ! 1919: given element type, the contents of all those provided are merged. When ! 1920: more than one definition is provided for the same attribute of a ! 1921: given element type, the first declaration is binding and later ! 1922: declarations are ignored. ! 1923: <termref def='dt-interop'>For interoperability,</termref> writers of DTDs ! 1924: may choose to provide at most one attribute-list declaration ! 1925: for a given element type, at most one attribute definition ! 1926: for a given attribute name, and at least one attribute definition ! 1927: in each attribute-list declaration. ! 1928: For interoperability, an XML processor may at user option ! 1929: issue a warning when more than one attribute-list declaration is ! 1930: provided for a given element type, or more than one attribute definition ! 1931: is provided ! 1932: for a given attribute, but this is not an error. ! 1933: </p> ! 1934: ! 1935: <div3 id='sec-attribute-types'> ! 1936: <head>Attribute Types</head> ! 1937: ! 1938: <p>XML attribute types are of three kinds: a string type, a ! 1939: set of tokenized types, and enumerated types. The string type may take ! 1940: any literal string as a value; the tokenized types have varying lexical ! 1941: and semantic constraints, as noted: ! 1942: <scrap lang='ebnf'> ! 1943: <head>Attribute Types</head> ! 1944: <prodgroup pcw4="14" pcw5="11.5"> ! 1945: <prod id='NT-AttType'><lhs>AttType</lhs> ! 1946: <rhs><nt def='NT-StringType'>StringType</nt> ! 1947: | <nt def='NT-TokenizedType'>TokenizedType</nt> ! 1948: | <nt def='NT-EnumeratedType'>EnumeratedType</nt> ! 1949: </rhs> ! 1950: </prod> ! 1951: <prod id='NT-StringType'><lhs>StringType</lhs> ! 1952: <rhs>'CDATA'</rhs> ! 1953: </prod> ! 1954: <prod id='NT-TokenizedType'><lhs>TokenizedType</lhs> ! 1955: <rhs>'ID'</rhs> ! 1956: <vc def='id'/> ! 1957: <vc def='one-id-per-el'/> ! 1958: <vc def='id-default'/> ! 1959: <rhs>| 'IDREF'</rhs> ! 1960: <vc def='idref'/> ! 1961: <rhs>| 'IDREFS'</rhs> ! 1962: <vc def='idref'/> ! 1963: <rhs>| 'ENTITY'</rhs> ! 1964: <vc def='entname'/> ! 1965: <rhs>| 'ENTITIES'</rhs> ! 1966: <vc def='entname'/> ! 1967: <rhs>| 'NMTOKEN'</rhs> ! 1968: <vc def='nmtok'/> ! 1969: <rhs>| 'NMTOKENS'</rhs> ! 1970: <vc def='nmtok'/></prod> ! 1971: </prodgroup> ! 1972: </scrap> ! 1973: </p> ! 1974: <vcnote id='id' > ! 1975: <head>ID</head> ! 1976: <p> ! 1977: Values of type <kw>ID</kw> must match the ! 1978: <nt def='NT-Name'>Name</nt> production. ! 1979: A name must not appear more than once in ! 1980: an XML document as a value of this type; i.e., ID values must uniquely ! 1981: identify the elements which bear them. ! 1982: </p> ! 1983: </vcnote> ! 1984: <vcnote id='one-id-per-el'> ! 1985: <head>One ID per Element Type</head> ! 1986: <p>No element type may have more than one ID attribute specified.</p> ! 1987: </vcnote> ! 1988: <vcnote id='id-default'> ! 1989: <head>ID Attribute Default</head> ! 1990: <p>An ID attribute must have a declared default of <kw>#IMPLIED</kw> or ! 1991: <kw>#REQUIRED</kw>.</p> ! 1992: </vcnote> ! 1993: <vcnote id='idref'> ! 1994: <head>IDREF</head> ! 1995: <p> ! 1996: Values of type <kw>IDREF</kw> must match ! 1997: the <nt def="NT-Name">Name</nt> production, and ! 1998: values of type <kw>IDREFS</kw> must match ! 1999: <nt def="NT-Names">Names</nt>; ! 2000: each <nt def='NT-Name'>Name</nt> must match the value of an ID attribute on ! 2001: some element in the XML document; i.e. <kw>IDREF</kw> values must ! 2002: match the value of some ID attribute. ! 2003: </p> ! 2004: </vcnote> ! 2005: <vcnote id='entname'> ! 2006: <head>Entity Name</head> ! 2007: <p> ! 2008: Values of type <kw>ENTITY</kw> ! 2009: must match the <nt def="NT-Name">Name</nt> production, ! 2010: values of type <kw>ENTITIES</kw> must match ! 2011: <nt def="NT-Names">Names</nt>; ! 2012: each <nt def="NT-Name">Name</nt> must ! 2013: match the ! 2014: name of an <termref def="dt-unparsed">unparsed entity</termref> declared in the ! 2015: <termref def="dt-doctype">DTD</termref>. ! 2016: </p> ! 2017: </vcnote> ! 2018: <vcnote id='nmtok'> ! 2019: <head>Name Token</head> ! 2020: <p> ! 2021: Values of type <kw>NMTOKEN</kw> must match the ! 2022: <nt def="NT-Nmtoken">Nmtoken</nt> production; ! 2023: values of type <kw>NMTOKENS</kw> must ! 2024: match <termref def="NT-Nmtokens">Nmtokens</termref>. ! 2025: </p> ! 2026: </vcnote> ! 2027: <!-- why? ! 2028: <p>The XML processor must normalize attribute values before ! 2029: passing them to the application, as described in ! 2030: <specref ref="AVNormalize"/>.</p>--> ! 2031: <p><termdef id='dt-enumerated' term='Enumerated Attribute ! 2032: Values'><term>Enumerated attributes</term> can take one ! 2033: of a list of values provided in the declaration</termdef>. There are two ! 2034: kinds of enumerated types: ! 2035: <scrap lang='ebnf'> ! 2036: <head>Enumerated Attribute Types</head> ! 2037: <prod id='NT-EnumeratedType'><lhs>EnumeratedType</lhs> ! 2038: <rhs><nt def='NT-NotationType'>NotationType</nt> ! 2039: | <nt def='NT-Enumeration'>Enumeration</nt> ! 2040: </rhs></prod> ! 2041: <prod id='NT-NotationType'><lhs>NotationType</lhs> ! 2042: <rhs>'NOTATION' ! 2043: <nt def='NT-S'>S</nt> ! 2044: '(' ! 2045: <nt def='NT-S'>S</nt>? ! 2046: <nt def='NT-Name'>Name</nt> ! 2047: (<nt def='NT-S'>S</nt>? '|' <nt def='NT-S'>S</nt>? ! 2048: <nt def='NT-Name'>Name</nt>)* ! 2049: <nt def='NT-S'>S</nt>? ')' ! 2050: </rhs> ! 2051: <vc def='notatn' /></prod> ! 2052: <prod id='NT-Enumeration'><lhs>Enumeration</lhs> ! 2053: <rhs>'(' <nt def='NT-S'>S</nt>? ! 2054: <nt def='NT-Nmtoken'>Nmtoken</nt> ! 2055: (<nt def='NT-S'>S</nt>? '|' ! 2056: <nt def='NT-S'>S</nt>? ! 2057: <nt def='NT-Nmtoken'>Nmtoken</nt>)* ! 2058: <nt def='NT-S'>S</nt>? ! 2059: ')'</rhs> ! 2060: <vc def='enum'/></prod> ! 2061: </scrap> ! 2062: A <kw>NOTATION</kw> attribute identifies a ! 2063: <termref def='dt-notation'>notation</termref>, declared in the ! 2064: DTD with associated system and/or public identifiers, to ! 2065: be used in interpreting the element to which the attribute ! 2066: is attached. ! 2067: </p> ! 2068: ! 2069: <vcnote id='notatn'> ! 2070: <head>Notation Attributes</head> ! 2071: <p> ! 2072: Values of this type must match ! 2073: one of the <titleref href='Notations'>notation</titleref> names included in ! 2074: the declaration; all notation names in the declaration must ! 2075: be declared. ! 2076: </p> ! 2077: </vcnote> ! 2078: <vcnote id='enum'> ! 2079: <head>Enumeration</head> ! 2080: <p> ! 2081: Values of this type ! 2082: must match one of the <nt def='NT-Nmtoken'>Nmtoken</nt> tokens in the ! 2083: declaration. ! 2084: </p> ! 2085: </vcnote> ! 2086: <p><termref def='dt-interop'>For interoperability,</termref> the same ! 2087: <nt def='NT-Nmtoken'>Nmtoken</nt> should not occur more than once in the ! 2088: enumerated attribute types of a single element type. ! 2089: </p> ! 2090: </div3> ! 2091: ! 2092: <div3 id='sec-attr-defaults'> ! 2093: <head>Attribute Defaults</head> ! 2094: ! 2095: <p>An <termref def="dt-attdecl">attribute declaration</termref> provides ! 2096: information on whether ! 2097: the attribute's presence is required, and if not, how an XML processor should ! 2098: react if a declared attribute is absent in a document. ! 2099: <scrap lang='ebnf'> ! 2100: <head>Attribute Defaults</head> ! 2101: <prodgroup pcw4="14" pcw5="11.5"> ! 2102: <prod id='NT-DefaultDecl'><lhs>DefaultDecl</lhs> ! 2103: <rhs>'#REQUIRED' ! 2104: | '#IMPLIED' </rhs> ! 2105: <rhs>| (('#FIXED' S)? <nt def='NT-AttValue'>AttValue</nt>)</rhs> ! 2106: <vc def='RequiredAttr'/> ! 2107: <vc def='defattrvalid'/> ! 2108: <wfc def="CleanAttrVals"/> ! 2109: <vc def='FixedAttr'/> ! 2110: </prod> ! 2111: </prodgroup> ! 2112: </scrap> ! 2113: ! 2114: </p> ! 2115: <p>In an attribute declaration, <kw>#REQUIRED</kw> means that the ! 2116: attribute must always be provided, <kw>#IMPLIED</kw> that no default ! 2117: value is provided. ! 2118: <!-- not any more!! ! 2119: <kw>#IMPLIED</kw> means that if the attribute is omitted ! 2120: from an element of this type, ! 2121: the XML processor must inform the application ! 2122: that no value was specified; no constraint is placed on the behavior ! 2123: of the application. --> ! 2124: <termdef id="dt-default" term="Attribute Default">If the ! 2125: declaration ! 2126: is neither <kw>#REQUIRED</kw> nor <kw>#IMPLIED</kw>, then the ! 2127: <nt def='NT-AttValue'>AttValue</nt> value contains the declared ! 2128: <term>default</term> value; the <kw>#FIXED</kw> keyword states that ! 2129: the attribute must always have the default value. ! 2130: If a default value ! 2131: is declared, when an XML processor encounters an omitted attribute, it ! 2132: is to behave as though the attribute were present with ! 2133: the declared default value.</termdef></p> ! 2134: <vcnote id='RequiredAttr'> ! 2135: <head>Required Attribute</head> ! 2136: <p>If the default declaration is the keyword <kw>#REQUIRED</kw>, then ! 2137: the attribute must be specified for ! 2138: all elements of the type in the attribute-list declaration. ! 2139: </p></vcnote> ! 2140: <vcnote id='defattrvalid'> ! 2141: <head>Attribute Default Legal</head> ! 2142: <p> ! 2143: The declared ! 2144: default value must meet the lexical constraints of the declared attribute type. ! 2145: </p> ! 2146: </vcnote> ! 2147: <vcnote id='FixedAttr'> ! 2148: <head>Fixed Attribute Default</head> ! 2149: <p>If an attribute has a default value declared with the ! 2150: <kw>#FIXED</kw> keyword, instances of that attribute must ! 2151: match the default value. ! 2152: </p></vcnote> ! 2153: ! 2154: <p>Examples of attribute-list declarations: ! 2155: <eg><!ATTLIST termdef ! 2156: id ID #REQUIRED ! 2157: name CDATA #IMPLIED> ! 2158: <!ATTLIST list ! 2159: type (bullets|ordered|glossary) "ordered"> ! 2160: <!ATTLIST form ! 2161: method CDATA #FIXED "POST"></eg></p> ! 2162: </div3> ! 2163: <div3 id='AVNormalize'> ! 2164: <head>Attribute-Value Normalization</head> ! 2165: <p>Before the value of an attribute is passed to the application ! 2166: or checked for validity, the ! 2167: XML processor must normalize it as follows: ! 2168: <ulist> ! 2169: <item><p>a character reference is processed by appending the referenced ! 2170: character to the attribute value</p></item> ! 2171: <item><p>an entity reference is processed by recursively processing the ! 2172: replacement text of the entity</p></item> ! 2173: <item><p>a whitespace character (#x20, #xD, #xA, #x9) is processed by ! 2174: appending #x20 to the normalized value, except that only a single #x20 ! 2175: is appended for a "#xD#xA" sequence that is part of an external ! 2176: parsed entity or the literal entity value of an internal parsed ! 2177: entity</p></item> ! 2178: <item><p>other characters are processed by appending them to the normalized ! 2179: value</p> ! 2180: </item></ulist> ! 2181: </p> ! 2182: <p>If the declared value is not CDATA, then the XML processor must ! 2183: further process the normalized attribute value by discarding any ! 2184: leading and trailing space (#x20) characters, and by replacing ! 2185: sequences of space (#x20) characters by a single space (#x20) ! 2186: character.</p> ! 2187: <p> ! 2188: All attributes for which no declaration has been read should be treated ! 2189: by a non-validating parser as if declared ! 2190: <kw>CDATA</kw>. ! 2191: </p> ! 2192: </div3> ! 2193: </div2> ! 2194: <div2 id='sec-condition-sect'> ! 2195: <head>Conditional Sections</head> ! 2196: <p><termdef id='dt-cond-section' term='conditional section'> ! 2197: <term>Conditional sections</term> are portions of the ! 2198: <termref def='dt-doctype'>document type declaration external subset</termref> ! 2199: which are ! 2200: included in, or excluded from, the logical structure of the DTD based on ! 2201: the keyword which governs them.</termdef> ! 2202: <scrap lang='ebnf'> ! 2203: <head>Conditional Section</head> ! 2204: <prodgroup pcw2="9" pcw4="14.5"> ! 2205: <prod id='NT-conditionalSect'><lhs>conditionalSect</lhs> ! 2206: <rhs><nt def='NT-includeSect'>includeSect</nt> ! 2207: | <nt def='NT-ignoreSect'>ignoreSect</nt> ! 2208: </rhs> ! 2209: </prod> ! 2210: <prod id='NT-includeSect'><lhs>includeSect</lhs> ! 2211: <rhs>'<![' S? 'INCLUDE' S? '[' ! 2212: ! 2213: <nt def="NT-extSubsetDecl">extSubsetDecl</nt> ! 2214: ']]>' ! 2215: </rhs> ! 2216: </prod> ! 2217: <prod id='NT-ignoreSect'><lhs>ignoreSect</lhs> ! 2218: <rhs>'<![' S? 'IGNORE' S? '[' ! 2219: <nt def="NT-ignoreSectContents">ignoreSectContents</nt>* ! 2220: ']]>'</rhs> ! 2221: </prod> ! 2222: ! 2223: <prod id='NT-ignoreSectContents'><lhs>ignoreSectContents</lhs> ! 2224: <rhs><nt def='NT-Ignore'>Ignore</nt> ! 2225: ('<![' <nt def='NT-ignoreSectContents'>ignoreSectContents</nt> ']]>' ! 2226: <nt def='NT-Ignore'>Ignore</nt>)*</rhs></prod> ! 2227: <prod id='NT-Ignore'><lhs>Ignore</lhs> ! 2228: <rhs><nt def='NT-Char'>Char</nt>* - ! 2229: (<nt def='NT-Char'>Char</nt>* ('<![' | ']]>') ! 2230: <nt def='NT-Char'>Char</nt>*) ! 2231: </rhs></prod> ! 2232: ! 2233: </prodgroup> ! 2234: </scrap> ! 2235: </p> ! 2236: <p>Like the internal and external DTD subsets, a conditional section ! 2237: may contain one or more complete declarations, ! 2238: comments, processing instructions, ! 2239: or nested conditional sections, intermingled with white space. ! 2240: </p> ! 2241: <p>If the keyword of the ! 2242: conditional section is <kw>INCLUDE</kw>, then the contents of the conditional ! 2243: section are part of the DTD. ! 2244: If the keyword of the conditional ! 2245: section is <kw>IGNORE</kw>, then the contents of the conditional section are ! 2246: not logically part of the DTD. ! 2247: Note that for reliable parsing, the contents of even ignored ! 2248: conditional sections must be read in order to ! 2249: detect nested conditional sections and ensure that the end of the ! 2250: outermost (ignored) conditional section is properly detected. ! 2251: If a conditional section with a ! 2252: keyword of <kw>INCLUDE</kw> occurs within a larger conditional ! 2253: section with a keyword of <kw>IGNORE</kw>, both the outer and the ! 2254: inner conditional sections are ignored.</p> ! 2255: <p>If the keyword of the conditional section is a ! 2256: parameter-entity reference, the parameter entity must be replaced by its ! 2257: content before the processor decides whether to ! 2258: include or ignore the conditional section.</p> ! 2259: <p>An example: ! 2260: <eg><!ENTITY % draft 'INCLUDE' > ! 2261: <!ENTITY % final 'IGNORE' > ! 2262: ! 2263: <![%draft;[ ! 2264: <!ELEMENT book (comments*, title, body, supplements?)> ! 2265: ]]> ! 2266: <![%final;[ ! 2267: <!ELEMENT book (title, body, supplements?)> ! 2268: ]]> ! 2269: </eg> ! 2270: </p> ! 2271: </div2> ! 2272: ! 2273: ! 2274: <!-- ! 2275: <div2 id='sec-pass-to-app'> ! 2276: <head>XML Processor Treatment of Logical Structure</head> ! 2277: <p>When an XML processor encounters a start-tag, it must make ! 2278: at least the following information available to the application: ! 2279: <ulist> ! 2280: <item> ! 2281: <p>the element type's generic identifier</p> ! 2282: </item> ! 2283: <item> ! 2284: <p>the names of attributes known to apply to this element type ! 2285: (validating processors must make available names of all attributes ! 2286: declared for the element type; non-validating processors must ! 2287: make available at least the names of the attributes for which ! 2288: values are specified. ! 2289: </p> ! 2290: </item> ! 2291: </ulist> ! 2292: </p> ! 2293: </div2> ! 2294: --> ! 2295: ! 2296: </div1> ! 2297: <!-- &Entities; --> ! 2298: ! 2299: <div1 id='sec-physical-struct'> ! 2300: <head>Physical Structures</head> ! 2301: ! 2302: <p><termdef id="dt-entity" term="Entity">An XML document may consist ! 2303: of one or many storage units. These are called ! 2304: <term>entities</term>; they all have <term>content</term> and are all ! 2305: (except for the document entity, see below, and ! 2306: the <termref def='dt-doctype'>external DTD subset</termref>) ! 2307: identified by <term>name</term>. ! 2308: </termdef> ! 2309: Each XML document has one entity ! 2310: called the <termref def="dt-docent">document entity</termref>, which serves ! 2311: as the starting point for the <termref def="dt-xml-proc">XML ! 2312: processor</termref> and may contain the whole document.</p> ! 2313: <p>Entities may be either parsed or unparsed. ! 2314: <termdef id="dt-parsedent" term="Text Entity">A <term>parsed entity's</term> ! 2315: contents are referred to as its ! 2316: <termref def='dt-repltext'>replacement text</termref>; ! 2317: this <termref def="dt-text">text</termref> is considered an ! 2318: integral part of the document.</termdef></p> ! 2319: ! 2320: <p><termdef id="dt-unparsed" term="Unparsed Entity">An ! 2321: <term>unparsed entity</term> ! 2322: is a resource whose contents may or may not be ! 2323: <termref def='dt-text'>text</termref>, and if text, may not be XML. ! 2324: Each unparsed entity ! 2325: has an associated <termref ! 2326: def="dt-notation">notation</termref>, identified by name. ! 2327: Beyond a requirement ! 2328: that an XML processor make the identifiers for the entity and ! 2329: notation available to the application, ! 2330: XML places no constraints on the contents of unparsed entities.</termdef> ! 2331: </p> ! 2332: <p> ! 2333: Parsed entities are invoked by name using entity references; ! 2334: unparsed entities by name, given in the value of <kw>ENTITY</kw> ! 2335: or <kw>ENTITIES</kw> ! 2336: attributes.</p> ! 2337: <p><termdef id='gen-entity' term='general entity' ! 2338: ><term>General entities</term> ! 2339: are entities for use within the document content. ! 2340: In this specification, general entities are sometimes referred ! 2341: to with the unqualified term <emph>entity</emph> when this leads ! 2342: to no ambiguity.</termdef> ! 2343: <termdef id='dt-PE' term='Parameter entity'>Parameter entities ! 2344: are parsed entities for use within the DTD.</termdef> ! 2345: These two types of entities use different forms of reference and ! 2346: are recognized in different contexts. ! 2347: Furthermore, they occupy different namespaces; a parameter entity and ! 2348: a general entity with the same name are two distinct entities. ! 2349: </p> ! 2350: ! 2351: <div2 id='sec-references'> ! 2352: <head>Character and Entity References</head> ! 2353: <p><termdef id="dt-charref" term="Character Reference"> ! 2354: A <term>character reference</term> refers to a specific character in the ! 2355: ISO/IEC 10646 character set, for example one not directly accessible from ! 2356: available input devices. ! 2357: <scrap lang='ebnf'> ! 2358: <head>Character Reference</head> ! 2359: <prod id='NT-CharRef'><lhs>CharRef</lhs> ! 2360: <rhs>'&#' [0-9]+ ';' </rhs> ! 2361: <rhs>| '&hcro;' [0-9a-fA-F]+ ';'</rhs> ! 2362: <wfc def="wf-Legalchar"/> ! 2363: </prod> ! 2364: </scrap> ! 2365: <wfcnote id="wf-Legalchar"> ! 2366: <head>Legal Character</head> ! 2367: <p>Characters referred to using character references must ! 2368: match the production for ! 2369: <termref def="NT-Char">Char</termref>.</p> ! 2370: </wfcnote> ! 2371: If the character reference begins with "<code>&#x</code>", the digits and ! 2372: letters up to the terminating <code>;</code> provide a hexadecimal ! 2373: representation of the character's code point in ISO/IEC 10646. ! 2374: If it begins just with "<code>&#</code>", the digits up to the terminating ! 2375: <code>;</code> provide a decimal representation of the character's ! 2376: code point. ! 2377: </termdef> ! 2378: </p> ! 2379: <p><termdef id="dt-entref" term="Entity Reference">An <term>entity ! 2380: reference</term> refers to the content of a named entity.</termdef> ! 2381: <termdef id='dt-GERef' term='General Entity Reference'>References to ! 2382: parsed general entities ! 2383: use ampersand (<code>&</code>) and semicolon (<code>;</code>) as ! 2384: delimiters.</termdef> ! 2385: <termdef id='dt-PERef' term='Parameter-entity reference'> ! 2386: <term>Parameter-entity references</term> use percent-sign (<code>%</code>) and ! 2387: semicolon ! 2388: (<code>;</code>) as delimiters.</termdef> ! 2389: </p> ! 2390: <scrap lang="ebnf"> ! 2391: <head>Entity Reference</head> ! 2392: <prod id='NT-Reference'><lhs>Reference</lhs> ! 2393: <rhs><nt def='NT-EntityRef'>EntityRef</nt> ! 2394: | <nt def='NT-CharRef'>CharRef</nt></rhs></prod> ! 2395: <prod id='NT-EntityRef'><lhs>EntityRef</lhs> ! 2396: <rhs>'&' <nt def='NT-Name'>Name</nt> ';'</rhs> ! 2397: <wfc def='wf-entdeclared'/> ! 2398: <vc def='vc-entdeclared'/> ! 2399: <wfc def='textent'/> ! 2400: <wfc def='norecursion'/> ! 2401: </prod> ! 2402: <prod id='NT-PEReference'><lhs>PEReference</lhs> ! 2403: <rhs>'%' <nt def='NT-Name'>Name</nt> ';'</rhs> ! 2404: <vc def='vc-entdeclared'/> ! 2405: <wfc def='norecursion'/> ! 2406: <wfc def='indtd'/> ! 2407: </prod> ! 2408: </scrap> ! 2409: ! 2410: <wfcnote id='wf-entdeclared'> ! 2411: <head>Entity Declared</head> ! 2412: <p>In a document without any DTD, a document with only an internal ! 2413: DTD subset which contains no parameter entity references, or a document with ! 2414: "<code>standalone='yes'</code>", ! 2415: the <nt def='NT-Name'>Name</nt> given in the entity reference must ! 2416: <termref def="dt-match">match</termref> that in an ! 2417: <titleref href='sec-entity-decl'>entity declaration</titleref>, except that ! 2418: well-formed documents need not declare ! 2419: any of the following entities: &magicents;. ! 2420: The declaration of a parameter entity must precede any reference to it. ! 2421: Similarly, the declaration of a general entity must precede any ! 2422: reference to it which appears in a default value in an attribute-list ! 2423: declaration.</p> ! 2424: <p>Note that if entities are declared in the external subset or in ! 2425: external parameter entities, a non-validating processor is ! 2426: <titleref href='include-if-valid'>not obligated to</titleref> read ! 2427: and process their declarations; for such documents, the rule that ! 2428: an entity must be declared is a well-formedness constraint only ! 2429: if <titleref href='sec-rmd'>standalone='yes'</titleref>.</p> ! 2430: </wfcnote> ! 2431: <vcnote id="vc-entdeclared"> ! 2432: <head>Entity Declared</head> ! 2433: <p>In a document with an external subset or external parameter ! 2434: entities with "<code>standalone='no'</code>", ! 2435: the <nt def='NT-Name'>Name</nt> given in the entity reference must <termref ! 2436: def="dt-match">match</termref> that in an ! 2437: <titleref href='sec-entity-decl'>entity declaration</titleref>. ! 2438: For interoperability, valid documents should declare the entities ! 2439: &magicents;, in the form ! 2440: specified in <specref ref="sec-predefined-ent"/>. ! 2441: The declaration of a parameter entity must precede any reference to it. ! 2442: Similarly, the declaration of a general entity must precede any ! 2443: reference to it which appears in a default value in an attribute-list ! 2444: declaration.</p> ! 2445: </vcnote> ! 2446: <!-- FINAL EDIT: is this duplication too clumsy? --> ! 2447: <wfcnote id='textent'> ! 2448: <head>Parsed Entity</head> ! 2449: <p> ! 2450: An entity reference must not contain the name of an <termref ! 2451: def="dt-unparsed">unparsed entity</termref>. Unparsed entities may be referred ! 2452: to only in <termref def="dt-attrval">attribute values</termref> declared to ! 2453: be of type <kw>ENTITY</kw> or <kw>ENTITIES</kw>. ! 2454: </p> ! 2455: </wfcnote> ! 2456: <wfcnote id='norecursion'> ! 2457: <head>No Recursion</head> ! 2458: <p> ! 2459: A parsed entity must not contain a recursive reference to itself, ! 2460: either directly or indirectly. ! 2461: </p> ! 2462: </wfcnote> ! 2463: <wfcnote id='indtd'> ! 2464: <head>In DTD</head> ! 2465: <p> ! 2466: Parameter-entity references may only appear in the ! 2467: <termref def='dt-doctype'>DTD</termref>. ! 2468: </p> ! 2469: </wfcnote> ! 2470: <p>Examples of character and entity references: ! 2471: <eg>Type <key>less-than</key> (&hcro;3C;) to save options. ! 2472: This document was prepared on &docdate; and ! 2473: is classified &security-level;.</eg></p> ! 2474: <p>Example of a parameter-entity reference: ! 2475: <eg><![CDATA[<!-- declare the parameter entity "ISOLat2"... --> ! 2476: <!ENTITY % ISOLat2 ! 2477: SYSTEM "http://www.xml.com/iso/isolat2-xml.entities" > ! 2478: <!-- ... now reference it. --> ! 2479: %ISOLat2;]]></eg></p> ! 2480: </div2> ! 2481: ! 2482: <div2 id='sec-entity-decl'> ! 2483: <head>Entity Declarations</head> ! 2484: ! 2485: <p><termdef id="dt-entdecl" term="entity declaration"> ! 2486: Entities are declared thus: ! 2487: <scrap lang='ebnf'> ! 2488: <head>Entity Declaration</head> ! 2489: <prodgroup pcw2="5" pcw4="18.5"> ! 2490: <prod id='NT-EntityDecl'><lhs>EntityDecl</lhs> ! 2491: <rhs><nt def="NT-GEDecl">GEDecl</nt><!--</rhs><com>General entities</com> ! 2492: <rhs>--> | <nt def="NT-PEDecl">PEDecl</nt></rhs> ! 2493: <!--<com>Parameter entities</com>--> ! 2494: </prod> ! 2495: <prod id='NT-GEDecl'><lhs>GEDecl</lhs> ! 2496: <rhs>'<!ENTITY' <nt def='NT-S'>S</nt> <nt def='NT-Name'>Name</nt> ! 2497: <nt def='NT-S'>S</nt> <nt def='NT-EntityDef'>EntityDef</nt> ! 2498: <nt def='NT-S'>S</nt>? '>'</rhs> ! 2499: </prod> ! 2500: <prod id='NT-PEDecl'><lhs>PEDecl</lhs> ! 2501: <rhs>'<!ENTITY' <nt def='NT-S'>S</nt> '%' <nt def='NT-S'>S</nt> ! 2502: <nt def='NT-Name'>Name</nt> <nt def='NT-S'>S</nt> ! 2503: <nt def='NT-PEDef'>PEDef</nt> <nt def='NT-S'>S</nt>? '>'</rhs> ! 2504: <!--<com>Parameter entities</com>--> ! 2505: </prod> ! 2506: <prod id='NT-EntityDef'><lhs>EntityDef</lhs> ! 2507: <rhs><nt def='NT-EntityValue'>EntityValue</nt> ! 2508: <!--</rhs> ! 2509: <rhs>-->| (<nt def='NT-ExternalID'>ExternalID</nt> ! 2510: <nt def='NT-NDataDecl'>NDataDecl</nt>?)</rhs> ! 2511: <!-- <nt def='NT-ExternalDef'>ExternalDef</nt></rhs> --> ! 2512: </prod> ! 2513: <!-- FINAL EDIT: what happened to WFs here? --> ! 2514: <prod id='NT-PEDef'><lhs>PEDef</lhs> ! 2515: <rhs><nt def='NT-EntityValue'>EntityValue</nt> ! 2516: | <nt def='NT-ExternalID'>ExternalID</nt></rhs></prod> ! 2517: </prodgroup> ! 2518: </scrap> ! 2519: The <nt def='NT-Name'>Name</nt> identifies the entity in an ! 2520: <termref def="dt-entref">entity reference</termref> or, in the case of an ! 2521: unparsed entity, in the value of an <kw>ENTITY</kw> or <kw>ENTITIES</kw> ! 2522: attribute. ! 2523: If the same entity is declared more than once, the first declaration ! 2524: encountered is binding; at user option, an XML processor may issue a ! 2525: warning if entities are declared multiple times.</termdef> ! 2526: </p> ! 2527: ! 2528: <div3 id='sec-internal-ent'> ! 2529: <head>Internal Entities</head> ! 2530: ! 2531: <p><termdef id='dt-internent' term="Internal Entity Replacement Text">If ! 2532: the entity definition is an ! 2533: <nt def='NT-EntityValue'>EntityValue</nt>, ! 2534: the defined entity is called an <term>internal entity</term>. ! 2535: There is no separate physical ! 2536: storage object, and the content of the entity is given in the ! 2537: declaration. </termdef> ! 2538: Note that some processing of entity and character references in the ! 2539: <termref def='dt-litentval'>literal entity value</termref> may be required to ! 2540: produce the correct <termref def='dt-repltext'>replacement ! 2541: text</termref>: see <specref ref='intern-replacement'/>. ! 2542: </p> ! 2543: <p>An internal entity is a <termref def="dt-parsedent">parsed ! 2544: entity</termref>.</p> ! 2545: <p>Example of an internal entity declaration: ! 2546: <eg><!ENTITY Pub-Status "This is a pre-release of the ! 2547: specification."></eg></p> ! 2548: </div3> ! 2549: ! 2550: <div3 id='sec-external-ent'> ! 2551: <head>External Entities</head> ! 2552: ! 2553: <p><termdef id="dt-extent" term="External Entity">If the entity is not ! 2554: internal, it is an <term>external ! 2555: entity</term>, declared as follows: ! 2556: <scrap lang='ebnf'> ! 2557: <head>External Entity Declaration</head> ! 2558: <!-- ! 2559: <prod id='NT-ExternalDef'><lhs>ExternalDef</lhs> ! 2560: <rhs></prod> --> ! 2561: <prod id='NT-ExternalID'><lhs>ExternalID</lhs> ! 2562: <rhs>'SYSTEM' <nt def='NT-S'>S</nt> ! 2563: <nt def='NT-SystemLiteral'>SystemLiteral</nt></rhs> ! 2564: <rhs>| 'PUBLIC' <nt def='NT-S'>S</nt> ! 2565: <nt def='NT-PubidLiteral'>PubidLiteral</nt> ! 2566: <nt def='NT-S'>S</nt> ! 2567: <nt def='NT-SystemLiteral'>SystemLiteral</nt> ! 2568: </rhs> ! 2569: </prod> ! 2570: <prod id='NT-NDataDecl'><lhs>NDataDecl</lhs> ! 2571: <rhs><nt def='NT-S'>S</nt> 'NDATA' <nt def='NT-S'>S</nt> ! 2572: <nt def='NT-Name'>Name</nt></rhs> ! 2573: <vc def='not-declared'/></prod> ! 2574: </scrap> ! 2575: If the <nt def='NT-NDataDecl'>NDataDecl</nt> is present, this is a ! 2576: general <termref def="dt-unparsed">unparsed ! 2577: entity</termref>; otherwise it is a parsed entity.</termdef></p> ! 2578: <vcnote id='not-declared'> ! 2579: <head>Notation Declared</head> ! 2580: <p> ! 2581: The <nt def='NT-Name'>Name</nt> must match the declared name of a ! 2582: <termref def="dt-notation">notation</termref>. ! 2583: </p> ! 2584: </vcnote> ! 2585: <p><termdef id="dt-sysid" term="System Identifier">The ! 2586: <nt def='NT-SystemLiteral'>SystemLiteral</nt> ! 2587: is called the entity's <term>system identifier</term>. It is a URI, ! 2588: which may be used to retrieve the entity.</termdef> ! 2589: Note that the hash mark (<code>#</code>) and fragment identifier ! 2590: frequently used with URIs are not, formally, part of the URI itself; ! 2591: an XML processor may signal an error if a fragment identifier is ! 2592: given as part of a system identifier. ! 2593: Unless otherwise provided by information outside the scope of this ! 2594: specification (e.g. a special XML element type defined by a particular ! 2595: DTD, or a processing instruction defined by a particular application ! 2596: specification), relative URIs are relative to the location of the ! 2597: resource within which the entity declaration occurs. ! 2598: A URI might thus be relative to the ! 2599: <termref def='dt-docent'>document entity</termref>, to the entity ! 2600: containing the <termref def='dt-doctype'>external DTD subset</termref>, ! 2601: or to some other <termref def='dt-extent'>external parameter entity</termref>. ! 2602: </p> ! 2603: <p>An XML processor should handle a non-ASCII character in a URI by ! 2604: representing the character in UTF-8 as one or more bytes, and then ! 2605: escaping these bytes with the URI escaping mechanism (i.e., by ! 2606: converting each byte to %HH, where HH is the hexadecimal notation of the ! 2607: byte value).</p> ! 2608: <p><termdef id="dt-pubid" term="Public identifier"> ! 2609: In addition to a system identifier, an external identifier may ! 2610: include a <term>public identifier</term>.</termdef> ! 2611: An XML processor attempting to retrieve the entity's content may use the public ! 2612: identifier to try to generate an alternative URI. If the processor ! 2613: is unable to do so, it must use the URI specified in the system ! 2614: literal. Before a match is attempted, all strings ! 2615: of white space in the public identifier must be normalized to single space characters (#x20), ! 2616: and leading and trailing white space must be removed.</p> ! 2617: <p>Examples of external entity declarations: ! 2618: <eg><!ENTITY open-hatch ! 2619: SYSTEM "http://www.textuality.com/boilerplate/OpenHatch.xml"> ! 2620: <!ENTITY open-hatch ! 2621: PUBLIC "-//Textuality//TEXT Standard open-hatch boilerplate//EN" ! 2622: "http://www.textuality.com/boilerplate/OpenHatch.xml"> ! 2623: <!ENTITY hatch-pic ! 2624: SYSTEM "../grafix/OpenHatch.gif" ! 2625: NDATA gif ></eg></p> ! 2626: </div3> ! 2627: ! 2628: </div2> ! 2629: ! 2630: <div2 id='TextEntities'> ! 2631: <head>Parsed Entities</head> ! 2632: <div3 id='sec-TextDecl'> ! 2633: <head>The Text Declaration</head> ! 2634: <p>External parsed entities may each begin with a <term>text ! 2635: declaration</term>. ! 2636: <scrap lang='ebnf'> ! 2637: <head>Text Declaration</head> ! 2638: <prodgroup pcw4="12.5" pcw5="13"> ! 2639: <prod id='NT-TextDecl'><lhs>TextDecl</lhs> ! 2640: <rhs>&xmlpio; ! 2641: <nt def='NT-VersionInfo'>VersionInfo</nt>? ! 2642: <nt def='NT-EncodingDecl'>EncodingDecl</nt> ! 2643: <nt def='NT-S'>S</nt>? &pic;</rhs> ! 2644: </prod> ! 2645: </prodgroup> ! 2646: </scrap> ! 2647: </p> ! 2648: <p>The text declaration must be provided literally, not ! 2649: by reference to a parsed entity. ! 2650: No text declaration may appear at any position other than the beginning of ! 2651: an external parsed entity.</p> ! 2652: </div3> ! 2653: <div3 id='wf-entities'> ! 2654: <head>Well-Formed Parsed Entities</head> ! 2655: <p>The document entity is well-formed if it matches the production labeled ! 2656: <nt def='NT-document'>document</nt>. ! 2657: An external general ! 2658: parsed entity is well-formed if it matches the production labeled ! 2659: <nt def='NT-extParsedEnt'>extParsedEnt</nt>. ! 2660: An external parameter ! 2661: entity is well-formed if it matches the production labeled ! 2662: <nt def='NT-extPE'>extPE</nt>. ! 2663: <scrap lang='ebnf'> ! 2664: <head>Well-Formed External Parsed Entity</head> ! 2665: <prod id='NT-extParsedEnt'><lhs>extParsedEnt</lhs> ! 2666: <rhs><nt def='NT-TextDecl'>TextDecl</nt>? ! 2667: <nt def='NT-content'>content</nt></rhs> ! 2668: </prod> ! 2669: <prod id='NT-extPE'><lhs>extPE</lhs> ! 2670: <rhs><nt def='NT-TextDecl'>TextDecl</nt>? ! 2671: <nt def='NT-extSubsetDecl'>extSubsetDecl</nt></rhs> ! 2672: </prod> ! 2673: </scrap> ! 2674: An internal general parsed entity is well-formed if its replacement text ! 2675: matches the production labeled ! 2676: <nt def='NT-content'>content</nt>. ! 2677: All internal parameter entities are well-formed by definition. ! 2678: </p> ! 2679: <p>A consequence of well-formedness in entities is that the logical ! 2680: and physical structures in an XML document are properly nested; no ! 2681: <termref def='dt-stag'>start-tag</termref>, ! 2682: <termref def='dt-etag'>end-tag</termref>, ! 2683: <termref def="dt-empty">empty-element tag</termref>, ! 2684: <termref def='dt-element'>element</termref>, ! 2685: <termref def='dt-comment'>comment</termref>, ! 2686: <termref def='dt-pi'>processing instruction</termref>, ! 2687: <termref def='dt-charref'>character ! 2688: reference</termref>, or ! 2689: <termref def='dt-entref'>entity reference</termref> ! 2690: can begin in one entity and end in another.</p> ! 2691: </div3> ! 2692: <div3 id='charencoding'> ! 2693: <head>Character Encoding in Entities</head> ! 2694: ! 2695: <p>Each external parsed entity in an XML document may use a different ! 2696: encoding for its characters. All XML processors must be able to read ! 2697: entities in either UTF-8 or UTF-16. ! 2698: ! 2699: </p> ! 2700: <p>Entities encoded in UTF-16 must ! 2701: begin with the Byte Order Mark described by ISO/IEC 10646 Annex E and ! 2702: Unicode Appendix B (the ZERO WIDTH NO-BREAK SPACE character, #xFEFF). ! 2703: This is an encoding signature, not part of either the markup or the ! 2704: character data of the XML document. ! 2705: XML processors must be able to use this character to ! 2706: differentiate between UTF-8 and UTF-16 encoded documents.</p> ! 2707: <p>Although an XML processor is required to read only entities in ! 2708: the UTF-8 and UTF-16 encodings, it is recognized that other encodings are ! 2709: used around the world, and it may be desired for XML processors ! 2710: to read entities that use them. ! 2711: Parsed entities which are stored in an encoding other than ! 2712: UTF-8 or UTF-16 must begin with a <titleref href='TextDecl'>text ! 2713: declaration</titleref> containing an encoding declaration: ! 2714: <scrap lang='ebnf'> ! 2715: <head>Encoding Declaration</head> ! 2716: <prod id='NT-EncodingDecl'><lhs>EncodingDecl</lhs> ! 2717: <rhs><nt def="NT-S">S</nt> ! 2718: 'encoding' <nt def='NT-Eq'>Eq</nt> ! 2719: ('"' <nt def='NT-EncName'>EncName</nt> '"' | ! 2720: "'" <nt def='NT-EncName'>EncName</nt> "'" ) ! 2721: </rhs> ! 2722: </prod> ! 2723: <prod id='NT-EncName'><lhs>EncName</lhs> ! 2724: <rhs>[A-Za-z] ([A-Za-z0-9._] | '-')*</rhs> ! 2725: <com>Encoding name contains only Latin characters</com> ! 2726: </prod> ! 2727: </scrap> ! 2728: In the <termref def='dt-docent'>document entity</termref>, the encoding ! 2729: declaration is part of the <termref def="dt-xmldecl">XML declaration</termref>. ! 2730: The <nt def="NT-EncName">EncName</nt> is the name of the encoding used. ! 2731: </p> ! 2732: <!-- FINAL EDIT: check name of IANA and charset names --> ! 2733: <p>In an encoding declaration, the values ! 2734: "<code>UTF-8</code>", ! 2735: "<code>UTF-16</code>", ! 2736: "<code>ISO-10646-UCS-2</code>", and ! 2737: "<code>ISO-10646-UCS-4</code>" should be ! 2738: used for the various encodings and transformations of Unicode / ! 2739: ISO/IEC 10646, the values ! 2740: "<code>ISO-8859-1</code>", ! 2741: "<code>ISO-8859-2</code>", ... ! 2742: "<code>ISO-8859-9</code>" should be used for the parts of ISO 8859, and ! 2743: the values ! 2744: "<code>ISO-2022-JP</code>", ! 2745: "<code>Shift_JIS</code>", and ! 2746: "<code>EUC-JP</code>" ! 2747: should be used for the various encoded forms of JIS X-0208-1997. XML ! 2748: processors may recognize other encodings; it is recommended that ! 2749: character encodings registered (as <emph>charset</emph>s) ! 2750: with the Internet Assigned Numbers ! 2751: Authority <bibref ref='IANA'/>, other than those just listed, should be ! 2752: referred to ! 2753: using their registered names. ! 2754: Note that these registered names are defined to be ! 2755: case-insensitive, so processors wishing to match against them ! 2756: should do so in a case-insensitive ! 2757: way.</p> ! 2758: <p>In the absence of information provided by an external ! 2759: transport protocol (e.g. HTTP or MIME), ! 2760: it is an <termref def="dt-error">error</termref> for an entity including ! 2761: an encoding declaration to be presented to the XML processor ! 2762: in an encoding other than that named in the declaration, ! 2763: for an encoding declaration to occur other than at the beginning ! 2764: of an external entity, or for ! 2765: an entity which begins with neither a Byte Order Mark nor an encoding ! 2766: declaration to use an encoding other than UTF-8. ! 2767: Note that since ASCII ! 2768: is a subset of UTF-8, ordinary ASCII entities do not strictly need ! 2769: an encoding declaration.</p> ! 2770: ! 2771: <p>It is a <termref def='dt-fatal'>fatal error</termref> when an XML processor ! 2772: encounters an entity with an encoding that it is unable to process.</p> ! 2773: <p>Examples of encoding declarations: ! 2774: <eg><?xml encoding='UTF-8'?> ! 2775: <?xml encoding='EUC-JP'?></eg></p> ! 2776: </div3> ! 2777: </div2> ! 2778: <div2 id='entproc'> ! 2779: <head>XML Processor Treatment of Entities and References</head> ! 2780: <p>The table below summarizes the contexts in which character references, ! 2781: entity references, and invocations of unparsed entities might appear and the ! 2782: required behavior of an <termref def='dt-xml-proc'>XML processor</termref> in ! 2783: each case. ! 2784: The labels in the leftmost column describe the recognition context: ! 2785: <glist> ! 2786: <gitem><label>Reference in Content</label> ! 2787: <def><p>as a reference ! 2788: anywhere after the <termref def='dt-stag'>start-tag</termref> and ! 2789: before the <termref def='dt-etag'>end-tag</termref> of an element; corresponds ! 2790: to the nonterminal <nt def='NT-content'>content</nt>.</p></def> ! 2791: </gitem> ! 2792: <gitem> ! 2793: <label>Reference in Attribute Value</label> ! 2794: <def><p>as a reference within either the value of an attribute in a ! 2795: <termref def='dt-stag'>start-tag</termref>, or a default ! 2796: value in an <termref def='dt-attdecl'>attribute declaration</termref>; ! 2797: corresponds to the nonterminal ! 2798: <nt def='NT-AttValue'>AttValue</nt>.</p></def></gitem> ! 2799: <gitem> ! 2800: <label>Occurs as Attribute Value</label> ! 2801: <def><p>as a <nt def='NT-Name'>Name</nt>, not a reference, appearing either as ! 2802: the value of an ! 2803: attribute which has been declared as type <kw>ENTITY</kw>, or as one of ! 2804: the space-separated tokens in the value of an attribute which has been ! 2805: declared as type <kw>ENTITIES</kw>.</p> ! 2806: </def></gitem> ! 2807: <gitem><label>Reference in Entity Value</label> ! 2808: <def><p>as a reference ! 2809: within a parameter or internal entity's ! 2810: <termref def='dt-litentval'>literal entity value</termref> in ! 2811: the entity's declaration; corresponds to the nonterminal ! 2812: <nt def='NT-EntityValue'>EntityValue</nt>.</p></def></gitem> ! 2813: <gitem><label>Reference in DTD</label> ! 2814: <def><p>as a reference within either the internal or external subsets of the ! 2815: <termref def='dt-doctype'>DTD</termref>, but outside ! 2816: of an <nt def='NT-EntityValue'>EntityValue</nt> or ! 2817: <nt def="NT-AttValue">AttValue</nt>.</p></def> ! 2818: </gitem> ! 2819: </glist></p> ! 2820: <htable border='1' cellpadding='7' align='center'> ! 2821: <htbody> ! 2822: <tr><td bgcolor='&cellback;' rowspan='2' colspan='1'></td> ! 2823: <td bgcolor='&cellback;' align='center' valign='bottom' colspan='4'>Entity Type</td> ! 2824: <td bgcolor='&cellback;' rowspan='2' align='center'>Character</td> ! 2825: </tr> ! 2826: <tr align='center' valign='bottom'> ! 2827: <td bgcolor='&cellback;'>Parameter</td> ! 2828: <td bgcolor='&cellback;'>Internal ! 2829: General</td> ! 2830: <td bgcolor='&cellback;'>External Parsed ! 2831: General</td> ! 2832: <td bgcolor='&cellback;'>Unparsed</td> ! 2833: </tr> ! 2834: <tr align='center' valign='middle'> ! 2835: ! 2836: <td bgcolor='&cellback;' align='right'>Reference ! 2837: in Content</td> ! 2838: <td bgcolor='&cellback;'><titleref href='not-recognized'>Not recognized</titleref></td> ! 2839: <td bgcolor='&cellback;'><titleref href='included'>Included</titleref></td> ! 2840: <td bgcolor='&cellback;'><titleref href='include-if-valid'>Included if validating</titleref></td> ! 2841: <td bgcolor='&cellback;'><titleref href='forbidden'>Forbidden</titleref></td> ! 2842: <td bgcolor='&cellback;'><titleref href='included'>Included</titleref></td> ! 2843: </tr> ! 2844: <tr align='center' valign='middle'> ! 2845: <td bgcolor='&cellback;' align='right'>Reference ! 2846: in Attribute Value</td> ! 2847: <td bgcolor='&cellback;'><titleref href='not-recognized'>Not recognized</titleref></td> ! 2848: <td bgcolor='&cellback;'><titleref href='inliteral'>Included in literal</titleref></td> ! 2849: <td bgcolor='&cellback;'><titleref href='forbidden'>Forbidden</titleref></td> ! 2850: <td bgcolor='&cellback;'><titleref href='forbidden'>Forbidden</titleref></td> ! 2851: <td bgcolor='&cellback;'><titleref href='included'>Included</titleref></td> ! 2852: </tr> ! 2853: <tr align='center' valign='middle'> ! 2854: <td bgcolor='&cellback;' align='right'>Occurs as ! 2855: Attribute Value</td> ! 2856: <td bgcolor='&cellback;'><titleref href='not-recognized'>Not recognized</titleref></td> ! 2857: <td bgcolor='&cellback;'><titleref href='not-recognized'>Forbidden</titleref></td> ! 2858: <td bgcolor='&cellback;'><titleref href='not-recognized'>Forbidden</titleref></td> ! 2859: <td bgcolor='&cellback;'><titleref href='notify'>Notify</titleref></td> ! 2860: <td bgcolor='&cellback;'><titleref href='not recognized'>Not recognized</titleref></td> ! 2861: </tr> ! 2862: <tr align='center' valign='middle'> ! 2863: <td bgcolor='&cellback;' align='right'>Reference ! 2864: in EntityValue</td> ! 2865: <td bgcolor='&cellback;'><titleref href='inliteral'>Included in literal</titleref></td> ! 2866: <td bgcolor='&cellback;'><titleref href='bypass'>Bypassed</titleref></td> ! 2867: <td bgcolor='&cellback;'><titleref href='bypass'>Bypassed</titleref></td> ! 2868: <td bgcolor='&cellback;'><titleref href='forbidden'>Forbidden</titleref></td> ! 2869: <td bgcolor='&cellback;'><titleref href='included'>Included</titleref></td> ! 2870: </tr> ! 2871: <tr align='center' valign='middle'> ! 2872: <td bgcolor='&cellback;' align='right'>Reference ! 2873: in DTD</td> ! 2874: <td bgcolor='&cellback;'><titleref href='as-PE'>Included as PE</titleref></td> ! 2875: <td bgcolor='&cellback;'><titleref href='forbidden'>Forbidden</titleref></td> ! 2876: <td bgcolor='&cellback;'><titleref href='forbidden'>Forbidden</titleref></td> ! 2877: <td bgcolor='&cellback;'><titleref href='forbidden'>Forbidden</titleref></td> ! 2878: <td bgcolor='&cellback;'><titleref href='forbidden'>Forbidden</titleref></td> ! 2879: </tr> ! 2880: </htbody> ! 2881: </htable> ! 2882: <div3 id='not-recognized'> ! 2883: <head>Not Recognized</head> ! 2884: <p>Outside the DTD, the <code>%</code> character has no ! 2885: special significance; thus, what would be parameter entity references in the ! 2886: DTD are not recognized as markup in <nt def='NT-content'>content</nt>. ! 2887: Similarly, the names of unparsed entities are not recognized except ! 2888: when they appear in the value of an appropriately declared attribute. ! 2889: </p> ! 2890: </div3> ! 2891: <div3 id='included'> ! 2892: <head>Included</head> ! 2893: <p><termdef id="dt-include" term="Include">An entity is ! 2894: <term>included</term> when its ! 2895: <termref def='dt-repltext'>replacement text</termref> is retrieved ! 2896: and processed, in place of the reference itself, ! 2897: as though it were part of the document at the location the ! 2898: reference was recognized. ! 2899: The replacement text may contain both ! 2900: <termref def='dt-chardata'>character data</termref> ! 2901: and (except for parameter entities) <termref def="dt-markup">markup</termref>, ! 2902: which must be recognized in ! 2903: the usual way, except that the replacement text of entities used to escape ! 2904: markup delimiters (the entities &magicents;) is always treated as ! 2905: data. (The string "<code>AT&amp;T;</code>" expands to ! 2906: "<code>AT&T;</code>" and the remaining ampersand is not recognized ! 2907: as an entity-reference delimiter.) ! 2908: A character reference is <term>included</term> when the indicated ! 2909: character is processed in place of the reference itself. ! 2910: </termdef></p> ! 2911: </div3> ! 2912: <div3 id='include-if-valid'> ! 2913: <head>Included If Validating</head> ! 2914: <p>When an XML processor recognizes a reference to a parsed entity, in order ! 2915: to <termref def="dt-valid">validate</termref> ! 2916: the document, the processor must ! 2917: <termref def="dt-include">include</termref> its ! 2918: replacement text. ! 2919: If the entity is external, and the processor is not ! 2920: attempting to validate the XML document, the ! 2921: processor <termref def="dt-may">may</termref>, but need not, ! 2922: include the entity's replacement text. ! 2923: If a non-validating parser does not include the replacement text, ! 2924: it must inform the application that it recognized, but did not ! 2925: read, the entity.</p> ! 2926: <p>This rule is based on the recognition that the automatic inclusion ! 2927: provided by the SGML and XML entity mechanism, primarily designed ! 2928: to support modularity in authoring, is not necessarily ! 2929: appropriate for other applications, in particular document browsing. ! 2930: Browsers, for example, when encountering an external parsed entity reference, ! 2931: might choose to provide a visual indication of the entity's ! 2932: presence and retrieve it for display only on demand. ! 2933: </p> ! 2934: </div3> ! 2935: <div3 id='forbidden'> ! 2936: <head>Forbidden</head> ! 2937: <p>The following are forbidden, and constitute ! 2938: <termref def='dt-fatal'>fatal</termref> errors: ! 2939: <ulist> ! 2940: <item><p>the appearance of a reference to an ! 2941: <termref def='dt-unparsed'>unparsed entity</termref>. ! 2942: </p></item> ! 2943: <item><p>the appearance of any character or general-entity reference in the ! 2944: DTD except within an <nt def='NT-EntityValue'>EntityValue</nt> or ! 2945: <nt def="NT-AttValue">AttValue</nt>.</p></item> ! 2946: <item><p>a reference to an external entity in an attribute value.</p> ! 2947: </item> ! 2948: </ulist> ! 2949: </p> ! 2950: </div3> ! 2951: <div3 id='inliteral'> ! 2952: <head>Included in Literal</head> ! 2953: <p>When an <termref def='dt-entref'>entity reference</termref> appears in an ! 2954: attribute value, or a parameter entity reference appears in a literal entity ! 2955: value, its <termref def='dt-repltext'>replacement text</termref> is ! 2956: processed in place of the reference itself as though it ! 2957: were part of the document at the location the reference was recognized, ! 2958: except that a single or double quote character in the replacement text ! 2959: is always treated as a normal data character and will not terminate the ! 2960: literal. ! 2961: For example, this is well-formed: ! 2962: <eg><![CDATA[<!ENTITY % YN '"Yes"' > ! 2963: <!ENTITY WhatHeSaid "He said &YN;" >]]></eg> ! 2964: while this is not: ! 2965: <eg><!ENTITY EndAttr "27'" > ! 2966: <element attribute='a-&EndAttr;></eg> ! 2967: </p></div3> ! 2968: <div3 id='notify'> ! 2969: <head>Notify</head> ! 2970: <p>When the name of an <termref def='dt-unparsed'>unparsed ! 2971: entity</termref> appears as a token in the ! 2972: value of an attribute of declared type <kw>ENTITY</kw> or <kw>ENTITIES</kw>, ! 2973: a validating processor must inform the ! 2974: application of the <termref def='dt-sysid'>system</termref> ! 2975: and <termref def='dt-pubid'>public</termref> (if any) ! 2976: identifiers for both the entity and its associated ! 2977: <termref def="dt-notation">notation</termref>.</p> ! 2978: </div3> ! 2979: <div3 id='bypass'> ! 2980: <head>Bypassed</head> ! 2981: <p>When a general entity reference appears in the ! 2982: <nt def='NT-EntityValue'>EntityValue</nt> in an entity declaration, ! 2983: it is bypassed and left as is.</p> ! 2984: </div3> ! 2985: <div3 id='as-PE'> ! 2986: <head>Included as PE</head> ! 2987: <p>Just as with external parsed entities, parameter entities ! 2988: need only be <titleref href='include-if-valid'>included if ! 2989: validating</titleref>. ! 2990: When a parameter-entity reference is recognized in the DTD ! 2991: and included, its ! 2992: <termref def='dt-repltext'>replacement ! 2993: text</termref> is enlarged by the attachment of one leading and one following ! 2994: space (#x20) character; the intent is to constrain the replacement ! 2995: text of parameter ! 2996: entities to contain an integral number of grammatical tokens in the DTD. ! 2997: </p> ! 2998: </div3> ! 2999: ! 3000: </div2> ! 3001: <div2 id='intern-replacement'> ! 3002: <head>Construction of Internal Entity Replacement Text</head> ! 3003: <p>In discussing the treatment ! 3004: of internal entities, it is ! 3005: useful to distinguish two forms of the entity's value. ! 3006: <termdef id="dt-litentval" term='Literal Entity Value'>The <term>literal ! 3007: entity value</term> is the quoted string actually ! 3008: present in the entity declaration, corresponding to the ! 3009: non-terminal <nt def='NT-EntityValue'>EntityValue</nt>.</termdef> ! 3010: <termdef id='dt-repltext' term='Replacement Text'>The <term>replacement ! 3011: text</term> is the content of the entity, after ! 3012: replacement of character references and parameter-entity ! 3013: references. ! 3014: </termdef></p> ! 3015: ! 3016: <p>The literal entity value ! 3017: as given in an internal entity declaration ! 3018: (<nt def='NT-EntityValue'>EntityValue</nt>) may contain character, ! 3019: parameter-entity, and general-entity references. ! 3020: Such references must be contained entirely within the ! 3021: literal entity value. ! 3022: The actual replacement text that is ! 3023: <termref def='dt-include'>included</termref> as described above ! 3024: must contain the <emph>replacement text</emph> of any ! 3025: parameter entities referred to, and must contain the character ! 3026: referred to, in place of any character references in the ! 3027: literal entity value; however, ! 3028: general-entity references must be left as-is, unexpanded. ! 3029: For example, given the following declarations: ! 3030: ! 3031: <eg><![CDATA[<!ENTITY % pub "Éditions Gallimard" > ! 3032: <!ENTITY rights "All rights reserved" > ! 3033: <!ENTITY book "La Peste: Albert Camus, ! 3034: © 1947 %pub;. &rights;" >]]></eg> ! 3035: then the replacement text for the entity "<code>book</code>" is: ! 3036: <eg>La Peste: Albert Camus, ! 3037: © 1947 Éditions Gallimard. &rights;</eg> ! 3038: The general-entity reference "<code>&rights;</code>" would be expanded ! 3039: should the reference "<code>&book;</code>" appear in the document's ! 3040: content or an attribute value.</p> ! 3041: <p>These simple rules may have complex interactions; for a detailed ! 3042: discussion of a difficult example, see ! 3043: <specref ref='sec-entexpand'/>. ! 3044: </p> ! 3045: ! 3046: </div2> ! 3047: <div2 id='sec-predefined-ent'> ! 3048: <head>Predefined Entities</head> ! 3049: <p><termdef id="dt-escape" term="escape">Entity and character ! 3050: references can both be used to <term>escape</term> the left angle bracket, ! 3051: ampersand, and other delimiters. A set of general entities ! 3052: (&magicents;) is specified for this purpose. ! 3053: Numeric character references may also be used; they are ! 3054: expanded immediately when recognized and must be treated as ! 3055: character data, so the numeric character references ! 3056: "<code>&#60;</code>" and "<code>&#38;</code>" may be used to ! 3057: escape <code><</code> and <code>&</code> when they occur ! 3058: in character data.</termdef></p> ! 3059: <p>All XML processors must recognize these entities whether they ! 3060: are declared or not. ! 3061: <termref def='dt-interop'>For interoperability</termref>, ! 3062: valid XML documents should declare these ! 3063: entities, like any others, before using them. ! 3064: If the entities in question are declared, they must be declared ! 3065: as internal entities whose replacement text is the single ! 3066: character being escaped or a character reference to ! 3067: that character, as shown below. ! 3068: <eg><![CDATA[<!ENTITY lt "&#60;"> ! 3069: <!ENTITY gt ">"> ! 3070: <!ENTITY amp "&#38;"> ! 3071: <!ENTITY apos "'"> ! 3072: <!ENTITY quot """> ! 3073: ]]></eg> ! 3074: Note that the <code><</code> and <code>&</code> characters ! 3075: in the declarations of "<code>lt</code>" and "<code>amp</code>" ! 3076: are doubly escaped to meet the requirement that entity replacement ! 3077: be well-formed. ! 3078: </p> ! 3079: </div2> ! 3080: ! 3081: <div2 id='Notations'> ! 3082: <head>Notation Declarations</head> ! 3083: ! 3084: <p><termdef id="dt-notation" term="Notation"><term>Notations</term> identify by ! 3085: name the format of <termref def="dt-extent">unparsed ! 3086: entities</termref>, the ! 3087: format of elements which bear a notation attribute, ! 3088: or the application to which ! 3089: a <termref def="dt-pi">processing instruction</termref> is ! 3090: addressed.</termdef></p> ! 3091: <p><termdef id="dt-notdecl" term="Notation Declaration"> ! 3092: <term>Notation declarations</term> ! 3093: provide a name for the notation, for use in ! 3094: entity and attribute-list declarations and in attribute specifications, ! 3095: and an external identifier for the notation which may allow an XML ! 3096: processor or its client application to locate a helper application ! 3097: capable of processing data in the given notation. ! 3098: <scrap lang='ebnf'> ! 3099: <head>Notation Declarations</head> ! 3100: <prod id='NT-NotationDecl'><lhs>NotationDecl</lhs> ! 3101: <rhs>'<!NOTATION' <nt def='NT-S'>S</nt> <nt def='NT-Name'>Name</nt> ! 3102: <nt def='NT-S'>S</nt> ! 3103: (<nt def='NT-ExternalID'>ExternalID</nt> | ! 3104: <nt def='NT-PublicID'>PublicID</nt>) ! 3105: <nt def='NT-S'>S</nt>? '>'</rhs></prod> ! 3106: <prod id='NT-PublicID'><lhs>PublicID</lhs> ! 3107: <rhs>'PUBLIC' <nt def='NT-S'>S</nt> ! 3108: <nt def='NT-PubidLiteral'>PubidLiteral</nt> ! 3109: </rhs></prod> ! 3110: </scrap> ! 3111: </termdef></p> ! 3112: <p>XML processors must provide applications with the name and external ! 3113: identifier(s) of any notation declared and referred to in an attribute ! 3114: value, attribute definition, or entity declaration. They may ! 3115: additionally resolve the external identifier into the ! 3116: <termref def="dt-sysid">system identifier</termref>, ! 3117: file name, or other information needed to allow the ! 3118: application to call a processor for data in the notation described. (It ! 3119: is not an error, however, for XML documents to declare and refer to ! 3120: notations for which notation-specific applications are not available on ! 3121: the system where the XML processor or application is running.)</p> ! 3122: </div2> ! 3123: ! 3124: ! 3125: <div2 id='sec-doc-entity'> ! 3126: <head>Document Entity</head> ! 3127: ! 3128: <p><termdef id="dt-docent" term="Document Entity">The <term>document ! 3129: entity</term> serves as the root of the entity ! 3130: tree and a starting-point for an <termref def="dt-xml-proc">XML ! 3131: processor</termref>.</termdef> ! 3132: This specification does ! 3133: not specify how the document entity is to be located by an XML ! 3134: processor; unlike other entities, the document entity has no name and might ! 3135: well appear on a processor input stream ! 3136: without any identification at all.</p> ! 3137: </div2> ! 3138: ! 3139: ! 3140: </div1> ! 3141: <!-- &Conformance; --> ! 3142: ! 3143: <div1 id='sec-conformance'> ! 3144: <head>Conformance</head> ! 3145: ! 3146: <div2 id='proc-types'> ! 3147: <head>Validating and Non-Validating Processors</head> ! 3148: <p>Conforming <termref def="dt-xml-proc">XML processors</termref> fall into two ! 3149: classes: validating and non-validating.</p> ! 3150: <p>Validating and non-validating processors alike must report ! 3151: violations of this specification's well-formedness constraints ! 3152: in the content of the ! 3153: <termref def='dt-docent'>document entity</termref> and any ! 3154: other <termref def='dt-parsedent'>parsed entities</termref> that ! 3155: they read.</p> ! 3156: <p><termdef id="dt-validating" term="Validating Processor"> ! 3157: <term>Validating processors</term> must report ! 3158: violations of the constraints expressed by the declarations in the ! 3159: <termref def="dt-doctype">DTD</termref>, and ! 3160: failures to fulfill the validity constraints given ! 3161: in this specification. ! 3162: </termdef> ! 3163: To accomplish this, validating XML processors must read and process the entire ! 3164: DTD and all external parsed entities referenced in the document. ! 3165: </p> ! 3166: <p>Non-validating processors are required to check only the ! 3167: <termref def='dt-docent'>document entity</termref>, including ! 3168: the entire internal DTD subset, for well-formedness. ! 3169: <termdef id='dt-use-mdecl' term='Process Declarations'> ! 3170: While they are not required to check the document for validity, ! 3171: they are required to ! 3172: <term>process</term> all the declarations they read in the ! 3173: internal DTD subset and in any parameter entity that they ! 3174: read, up to the first reference ! 3175: to a parameter entity that they do <emph>not</emph> read; that is to ! 3176: say, they must ! 3177: use the information in those declarations to ! 3178: <titleref href='AVNormalize'>normalize</titleref> attribute values, ! 3179: <titleref href='included'>include</titleref> the replacement text of ! 3180: internal entities, and supply ! 3181: <titleref href='sec-attr-defaults'>default attribute values</titleref>. ! 3182: </termdef> ! 3183: They must not <termref def='dt-use-mdecl'>process</termref> ! 3184: <termref def='dt-entdecl'>entity declarations</termref> or ! 3185: <termref def='dt-attdecl'>attribute-list declarations</termref> ! 3186: encountered after a reference to a parameter entity that is not ! 3187: read, since the entity may have contained overriding declarations. ! 3188: </p> ! 3189: </div2> ! 3190: <div2 id='safe-behavior'> ! 3191: <head>Using XML Processors</head> ! 3192: <p>The behavior of a validating XML processor is highly predictable; it ! 3193: must read every piece of a document and report all well-formedness and ! 3194: validity violations. ! 3195: Less is required of a non-validating processor; it need not read any ! 3196: part of the document other than the document entity. ! 3197: This has two effects that may be important to users of XML processors: ! 3198: <ulist> ! 3199: <item><p>Certain well-formedness errors, specifically those that require ! 3200: reading external entities, may not be detected by a non-validating processor. ! 3201: Examples include the constraints entitled ! 3202: <titleref href='wf-entdeclared'>Entity Declared</titleref>, ! 3203: <titleref href='wf-textent'>Parsed Entity</titleref>, and ! 3204: <titleref href='wf-norecursion'>No Recursion</titleref>, as well ! 3205: as some of the cases described as ! 3206: <titleref href='forbidden'>forbidden</titleref> in ! 3207: <specref ref='entproc'/>.</p></item> ! 3208: <item><p>The information passed from the processor to the application may ! 3209: vary, depending on whether the processor reads ! 3210: parameter and external entities. ! 3211: For example, a non-validating processor may not ! 3212: <titleref href='AVNormalize'>normalize</titleref> attribute values, ! 3213: <titleref href='included'>include</titleref> the replacement text of ! 3214: internal entities, or supply ! 3215: <titleref href='sec-attr-defaults'>default attribute values</titleref>, ! 3216: where doing so depends on having read declarations in ! 3217: external or parameter entities.</p></item> ! 3218: </ulist> ! 3219: </p> ! 3220: <p>For maximum reliability in interoperating between different XML ! 3221: processors, applications which use non-validating processors should not ! 3222: rely on any behaviors not required of such processors. ! 3223: Applications which require facilities such as the use of default ! 3224: attributes or internal entities which are declared in external ! 3225: entities should use validating XML processors.</p> ! 3226: </div2> ! 3227: </div1> ! 3228: ! 3229: <div1 id='sec-notation'> ! 3230: <head>Notation</head> ! 3231: ! 3232: <p>The formal grammar of XML is given in this specification using a simple ! 3233: Extended Backus-Naur Form (EBNF) notation. Each rule in the grammar defines ! 3234: one symbol, in the form ! 3235: <eg>symbol ::= expression</eg></p> ! 3236: <p>Symbols are written with an initial capital letter if they are ! 3237: defined by a regular expression, or with an initial lower case letter ! 3238: otherwise. ! 3239: Literal strings are quoted. ! 3240: ! 3241: </p> ! 3242: ! 3243: <p>Within the expression on the right-hand side of a rule, the following ! 3244: expressions are used to match strings of one or more characters: ! 3245: <glist> ! 3246: <gitem> ! 3247: <label><code>#xN</code></label> ! 3248: <def><p>where <code>N</code> is a hexadecimal integer, the ! 3249: expression matches the character in ISO/IEC 10646 whose canonical ! 3250: (UCS-4) ! 3251: code value, when interpreted as an unsigned binary number, has ! 3252: the value indicated. The number of leading zeros in the ! 3253: <code>#xN</code> form is insignificant; the number of leading ! 3254: zeros in the corresponding code value ! 3255: is governed by the character ! 3256: encoding in use and is not significant for XML.</p></def> ! 3257: </gitem> ! 3258: <gitem> ! 3259: <label><code>[a-zA-Z]</code>, <code>[#xN-#xN]</code></label> ! 3260: <def><p>matches any <termref def='dt-character'>character</termref> ! 3261: with a value in the range(s) indicated (inclusive).</p></def> ! 3262: </gitem> ! 3263: <gitem> ! 3264: <label><code>[^a-z]</code>, <code>[^#xN-#xN]</code></label> ! 3265: <def><p>matches any <termref def='dt-character'>character</termref> ! 3266: with a value <emph>outside</emph> the ! 3267: range indicated.</p></def> ! 3268: </gitem> ! 3269: <gitem> ! 3270: <label><code>[^abc]</code>, <code>[^#xN#xN#xN]</code></label> ! 3271: <def><p>matches any <termref def='dt-character'>character</termref> ! 3272: with a value not among the characters given.</p></def> ! 3273: </gitem> ! 3274: <gitem> ! 3275: <label><code>"string"</code></label> ! 3276: <def><p>matches a literal string <termref def="dt-match">matching</termref> ! 3277: that given inside the double quotes.</p></def> ! 3278: </gitem> ! 3279: <gitem> ! 3280: <label><code>'string'</code></label> ! 3281: <def><p>matches a literal string <termref def="dt-match">matching</termref> ! 3282: that given inside the single quotes.</p></def> ! 3283: </gitem> ! 3284: </glist> ! 3285: These symbols may be combined to match more complex patterns as follows, ! 3286: where <code>A</code> and <code>B</code> represent simple expressions: ! 3287: <glist> ! 3288: <gitem> ! 3289: <label>(<code>expression</code>)</label> ! 3290: <def><p><code>expression</code> is treated as a unit ! 3291: and may be combined as described in this list.</p></def> ! 3292: </gitem> ! 3293: <gitem> ! 3294: <label><code>A?</code></label> ! 3295: <def><p>matches <code>A</code> or nothing; optional <code>A</code>.</p></def> ! 3296: </gitem> ! 3297: <gitem> ! 3298: <label><code>A B</code></label> ! 3299: <def><p>matches <code>A</code> followed by <code>B</code>.</p></def> ! 3300: </gitem> ! 3301: <gitem> ! 3302: <label><code>A | B</code></label> ! 3303: <def><p>matches <code>A</code> or <code>B</code> but not both.</p></def> ! 3304: </gitem> ! 3305: <gitem> ! 3306: <label><code>A - B</code></label> ! 3307: <def><p>matches any string that matches <code>A</code> but does not match ! 3308: <code>B</code>. ! 3309: </p></def> ! 3310: </gitem> ! 3311: <gitem> ! 3312: <label><code>A+</code></label> ! 3313: <def><p>matches one or more occurrences of <code>A</code>.</p></def> ! 3314: </gitem> ! 3315: <gitem> ! 3316: <label><code>A*</code></label> ! 3317: <def><p>matches zero or more occurrences of <code>A</code>.</p></def> ! 3318: </gitem> ! 3319: ! 3320: </glist> ! 3321: Other notations used in the productions are: ! 3322: <glist> ! 3323: <gitem> ! 3324: <label><code>/* ... */</code></label> ! 3325: <def><p>comment.</p></def> ! 3326: </gitem> ! 3327: <gitem> ! 3328: <label><code>[ wfc: ... ]</code></label> ! 3329: <def><p>well-formedness constraint; this identifies by name a ! 3330: constraint on ! 3331: <termref def="dt-wellformed">well-formed</termref> documents ! 3332: associated with a production.</p></def> ! 3333: </gitem> ! 3334: <gitem> ! 3335: <label><code>[ vc: ... ]</code></label> ! 3336: <def><p>validity constraint; this identifies by name a constraint on ! 3337: <termref def="dt-valid">valid</termref> documents associated with ! 3338: a production.</p></def> ! 3339: </gitem> ! 3340: </glist> ! 3341: </p></div1> ! 3342: ! 3343: </body> ! 3344: <back> ! 3345: <!-- &SGML; --> ! 3346: ! 3347: ! 3348: <!-- &Biblio; --> ! 3349: <div1 id='sec-bibliography'> ! 3350: ! 3351: <head>References</head> ! 3352: <div2 id='sec-existing-stds'> ! 3353: <head>Normative References</head> ! 3354: ! 3355: <blist> ! 3356: <bibl id='IANA' key='IANA'> ! 3357: (Internet Assigned Numbers Authority) <emph>Official Names for ! 3358: Character Sets</emph>, ! 3359: ed. Keld Simonsen et al. ! 3360: See <loc href='ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets'>ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets</loc>. ! 3361: </bibl> ! 3362: ! 3363: <bibl id='RFC1766' key='IETF RFC 1766'> ! 3364: IETF (Internet Engineering Task Force). ! 3365: <emph>RFC 1766: Tags for the Identification of Languages</emph>, ! 3366: ed. H. Alvestrand. ! 3367: 1995. ! 3368: </bibl> ! 3369: ! 3370: <bibl id='ISO639' key='ISO 639'> ! 3371: (International Organization for Standardization). ! 3372: <emph>ISO 639:1988 (E). ! 3373: Code for the representation of names of languages.</emph> ! 3374: [Geneva]: International Organization for ! 3375: Standardization, 1988.</bibl> ! 3376: ! 3377: <bibl id='ISO3166' key='ISO 3166'> ! 3378: (International Organization for Standardization). ! 3379: <emph>ISO 3166-1:1997 (E). ! 3380: Codes for the representation of names of countries and their subdivisions ! 3381: — Part 1: Country codes</emph> ! 3382: [Geneva]: International Organization for ! 3383: Standardization, 1997.</bibl> ! 3384: ! 3385: <bibl id='ISO10646' key='ISO/IEC 10646'>ISO ! 3386: (International Organization for Standardization). ! 3387: <emph>ISO/IEC 10646-1993 (E). Information technology — Universal ! 3388: Multiple-Octet Coded Character Set (UCS) — Part 1: ! 3389: Architecture and Basic Multilingual Plane.</emph> ! 3390: [Geneva]: International Organization for ! 3391: Standardization, 1993 (plus amendments AM 1 through AM 7). ! 3392: </bibl> ! 3393: ! 3394: <bibl id='Unicode' key='Unicode'>The Unicode Consortium. ! 3395: <emph>The Unicode Standard, Version 2.0.</emph> ! 3396: Reading, Mass.: Addison-Wesley Developers Press, 1996.</bibl> ! 3397: ! 3398: </blist> ! 3399: ! 3400: </div2> ! 3401: ! 3402: <div2><head>Other References</head> ! 3403: ! 3404: <blist> ! 3405: ! 3406: <bibl id='Aho' key='Aho/Ullman'>Aho, Alfred V., ! 3407: Ravi Sethi, and Jeffrey D. Ullman. ! 3408: <emph>Compilers: Principles, Techniques, and Tools</emph>. ! 3409: Reading: Addison-Wesley, 1986, rpt. corr. 1988.</bibl> ! 3410: ! 3411: <bibl id="Berners-Lee" xml-link="simple" key="Berners-Lee et al."> ! 3412: Berners-Lee, T., R. Fielding, and L. Masinter. ! 3413: <emph>Uniform Resource Identifiers (URI): Generic Syntax and ! 3414: Semantics</emph>. ! 3415: 1997. ! 3416: (Work in progress; see updates to RFC1738.)</bibl> ! 3417: ! 3418: <bibl id='ABK' key='Brüggemann-Klein'>Brüggemann-Klein, Anne. ! 3419: <emph>Regular Expressions into Finite Automata</emph>. ! 3420: Extended abstract in I. Simon, Hrsg., LATIN 1992, ! 3421: S. 97-98. Springer-Verlag, Berlin 1992. ! 3422: Full Version in Theoretical Computer Science 120: 197-213, 1993. ! 3423: ! 3424: </bibl> ! 3425: ! 3426: <bibl id='ABKDW' key='Brüggemann-Klein and Wood'>Brüggemann-Klein, Anne, ! 3427: and Derick Wood. ! 3428: <emph>Deterministic Regular Languages</emph>. ! 3429: Universität Freiburg, Institut für Informatik, ! 3430: Bericht 38, Oktober 1991. ! 3431: </bibl> ! 3432: ! 3433: <bibl id='Clark' key='Clark'>James Clark. ! 3434: Comparison of SGML and XML. See ! 3435: <loc href='http://www.w3.org/TR/NOTE-sgml-xml-971215'>http://www.w3.org/TR/NOTE-sgml-xml-971215</loc>. ! 3436: </bibl> ! 3437: <bibl id="RFC1738" xml-link="simple" key="IETF RFC1738"> ! 3438: IETF (Internet Engineering Task Force). ! 3439: <emph>RFC 1738: Uniform Resource Locators (URL)</emph>, ! 3440: ed. T. Berners-Lee, L. Masinter, M. McCahill. ! 3441: 1994. ! 3442: </bibl> ! 3443: ! 3444: <bibl id="RFC1808" xml-link="simple" key="IETF RFC1808"> ! 3445: IETF (Internet Engineering Task Force). ! 3446: <emph>RFC 1808: Relative Uniform Resource Locators</emph>, ! 3447: ed. R. Fielding. ! 3448: 1995. ! 3449: </bibl> ! 3450: ! 3451: <bibl id="RFC2141" xml-link="simple" key="IETF RFC2141"> ! 3452: IETF (Internet Engineering Task Force). ! 3453: <emph>RFC 2141: URN Syntax</emph>, ! 3454: ed. R. Moats. ! 3455: 1997. ! 3456: </bibl> ! 3457: ! 3458: <bibl id='ISO8879' key='ISO 8879'>ISO ! 3459: (International Organization for Standardization). ! 3460: <emph>ISO 8879:1986(E). Information processing — Text and Office ! 3461: Systems — Standard Generalized Markup Language (SGML).</emph> First ! 3462: edition — 1986-10-15. [Geneva]: International Organization for ! 3463: Standardization, 1986. ! 3464: </bibl> ! 3465: ! 3466: ! 3467: <bibl id='ISO10744' key='ISO/IEC 10744'>ISO ! 3468: (International Organization for Standardization). ! 3469: <emph>ISO/IEC 10744-1992 (E). Information technology — ! 3470: Hypermedia/Time-based Structuring Language (HyTime). ! 3471: </emph> ! 3472: [Geneva]: International Organization for ! 3473: Standardization, 1992. ! 3474: <emph>Extended Facilities Annexe.</emph> ! 3475: [Geneva]: International Organization for ! 3476: Standardization, 1996. ! 3477: </bibl> ! 3478: ! 3479: ! 3480: ! 3481: </blist> ! 3482: </div2> ! 3483: </div1> ! 3484: <div1 id='CharClasses'> ! 3485: <head>Character Classes</head> ! 3486: <p>Following the characteristics defined in the Unicode standard, ! 3487: characters are classed as base characters (among others, these ! 3488: contain the alphabetic characters of the Latin alphabet, without ! 3489: diacritics), ideographic characters, and combining characters (among ! 3490: others, this class contains most diacritics); these classes combine ! 3491: to form the class of letters. Digits and extenders are ! 3492: also distinguished. ! 3493: <scrap lang="ebnf" id="CHARACTERS"> ! 3494: <head>Characters</head> ! 3495: <prodgroup pcw3="3" pcw4="15"> ! 3496: <prod id="NT-Letter"><lhs>Letter</lhs> ! 3497: <rhs><nt def="NT-BaseChar">BaseChar</nt> ! 3498: | <nt def="NT-Ideographic">Ideographic</nt></rhs> </prod> ! 3499: <prod id='NT-BaseChar'><lhs>BaseChar</lhs> ! 3500: <rhs>[#x0041-#x005A] ! 3501: | [#x0061-#x007A] ! 3502: | [#x00C0-#x00D6] ! 3503: | [#x00D8-#x00F6] ! 3504: | [#x00F8-#x00FF] ! 3505: | [#x0100-#x0131] ! 3506: | [#x0134-#x013E] ! 3507: | [#x0141-#x0148] ! 3508: | [#x014A-#x017E] ! 3509: | [#x0180-#x01C3] ! 3510: | [#x01CD-#x01F0] ! 3511: | [#x01F4-#x01F5] ! 3512: | [#x01FA-#x0217] ! 3513: | [#x0250-#x02A8] ! 3514: | [#x02BB-#x02C1] ! 3515: | #x0386 ! 3516: | [#x0388-#x038A] ! 3517: | #x038C ! 3518: | [#x038E-#x03A1] ! 3519: | [#x03A3-#x03CE] ! 3520: | [#x03D0-#x03D6] ! 3521: | #x03DA ! 3522: | #x03DC ! 3523: | #x03DE ! 3524: | #x03E0 ! 3525: | [#x03E2-#x03F3] ! 3526: | [#x0401-#x040C] ! 3527: | [#x040E-#x044F] ! 3528: | [#x0451-#x045C] ! 3529: | [#x045E-#x0481] ! 3530: | [#x0490-#x04C4] ! 3531: | [#x04C7-#x04C8] ! 3532: | [#x04CB-#x04CC] ! 3533: | [#x04D0-#x04EB] ! 3534: | [#x04EE-#x04F5] ! 3535: | [#x04F8-#x04F9] ! 3536: | [#x0531-#x0556] ! 3537: | #x0559 ! 3538: | [#x0561-#x0586] ! 3539: | [#x05D0-#x05EA] ! 3540: | [#x05F0-#x05F2] ! 3541: | [#x0621-#x063A] ! 3542: | [#x0641-#x064A] ! 3543: | [#x0671-#x06B7] ! 3544: | [#x06BA-#x06BE] ! 3545: | [#x06C0-#x06CE] ! 3546: | [#x06D0-#x06D3] ! 3547: | #x06D5 ! 3548: | [#x06E5-#x06E6] ! 3549: | [#x0905-#x0939] ! 3550: | #x093D ! 3551: | [#x0958-#x0961] ! 3552: | [#x0985-#x098C] ! 3553: | [#x098F-#x0990] ! 3554: | [#x0993-#x09A8] ! 3555: | [#x09AA-#x09B0] ! 3556: | #x09B2 ! 3557: | [#x09B6-#x09B9] ! 3558: | [#x09DC-#x09DD] ! 3559: | [#x09DF-#x09E1] ! 3560: | [#x09F0-#x09F1] ! 3561: | [#x0A05-#x0A0A] ! 3562: | [#x0A0F-#x0A10] ! 3563: | [#x0A13-#x0A28] ! 3564: | [#x0A2A-#x0A30] ! 3565: | [#x0A32-#x0A33] ! 3566: | [#x0A35-#x0A36] ! 3567: | [#x0A38-#x0A39] ! 3568: | [#x0A59-#x0A5C] ! 3569: | #x0A5E ! 3570: | [#x0A72-#x0A74] ! 3571: | [#x0A85-#x0A8B] ! 3572: | #x0A8D ! 3573: | [#x0A8F-#x0A91] ! 3574: | [#x0A93-#x0AA8] ! 3575: | [#x0AAA-#x0AB0] ! 3576: | [#x0AB2-#x0AB3] ! 3577: | [#x0AB5-#x0AB9] ! 3578: | #x0ABD ! 3579: | #x0AE0 ! 3580: | [#x0B05-#x0B0C] ! 3581: | [#x0B0F-#x0B10] ! 3582: | [#x0B13-#x0B28] ! 3583: | [#x0B2A-#x0B30] ! 3584: | [#x0B32-#x0B33] ! 3585: | [#x0B36-#x0B39] ! 3586: | #x0B3D ! 3587: | [#x0B5C-#x0B5D] ! 3588: | [#x0B5F-#x0B61] ! 3589: | [#x0B85-#x0B8A] ! 3590: | [#x0B8E-#x0B90] ! 3591: | [#x0B92-#x0B95] ! 3592: | [#x0B99-#x0B9A] ! 3593: | #x0B9C ! 3594: | [#x0B9E-#x0B9F] ! 3595: | [#x0BA3-#x0BA4] ! 3596: | [#x0BA8-#x0BAA] ! 3597: | [#x0BAE-#x0BB5] ! 3598: | [#x0BB7-#x0BB9] ! 3599: | [#x0C05-#x0C0C] ! 3600: | [#x0C0E-#x0C10] ! 3601: | [#x0C12-#x0C28] ! 3602: | [#x0C2A-#x0C33] ! 3603: | [#x0C35-#x0C39] ! 3604: | [#x0C60-#x0C61] ! 3605: | [#x0C85-#x0C8C] ! 3606: | [#x0C8E-#x0C90] ! 3607: | [#x0C92-#x0CA8] ! 3608: | [#x0CAA-#x0CB3] ! 3609: | [#x0CB5-#x0CB9] ! 3610: | #x0CDE ! 3611: | [#x0CE0-#x0CE1] ! 3612: | [#x0D05-#x0D0C] ! 3613: | [#x0D0E-#x0D10] ! 3614: | [#x0D12-#x0D28] ! 3615: | [#x0D2A-#x0D39] ! 3616: | [#x0D60-#x0D61] ! 3617: | [#x0E01-#x0E2E] ! 3618: | #x0E30 ! 3619: | [#x0E32-#x0E33] ! 3620: | [#x0E40-#x0E45] ! 3621: | [#x0E81-#x0E82] ! 3622: | #x0E84 ! 3623: | [#x0E87-#x0E88] ! 3624: | #x0E8A ! 3625: | #x0E8D ! 3626: | [#x0E94-#x0E97] ! 3627: | [#x0E99-#x0E9F] ! 3628: | [#x0EA1-#x0EA3] ! 3629: | #x0EA5 ! 3630: | #x0EA7 ! 3631: | [#x0EAA-#x0EAB] ! 3632: | [#x0EAD-#x0EAE] ! 3633: | #x0EB0 ! 3634: | [#x0EB2-#x0EB3] ! 3635: | #x0EBD ! 3636: | [#x0EC0-#x0EC4] ! 3637: | [#x0F40-#x0F47] ! 3638: | [#x0F49-#x0F69] ! 3639: | [#x10A0-#x10C5] ! 3640: | [#x10D0-#x10F6] ! 3641: | #x1100 ! 3642: | [#x1102-#x1103] ! 3643: | [#x1105-#x1107] ! 3644: | #x1109 ! 3645: | [#x110B-#x110C] ! 3646: | [#x110E-#x1112] ! 3647: | #x113C ! 3648: | #x113E ! 3649: | #x1140 ! 3650: | #x114C ! 3651: | #x114E ! 3652: | #x1150 ! 3653: | [#x1154-#x1155] ! 3654: | #x1159 ! 3655: | [#x115F-#x1161] ! 3656: | #x1163 ! 3657: | #x1165 ! 3658: | #x1167 ! 3659: | #x1169 ! 3660: | [#x116D-#x116E] ! 3661: | [#x1172-#x1173] ! 3662: | #x1175 ! 3663: | #x119E ! 3664: | #x11A8 ! 3665: | #x11AB ! 3666: | [#x11AE-#x11AF] ! 3667: | [#x11B7-#x11B8] ! 3668: | #x11BA ! 3669: | [#x11BC-#x11C2] ! 3670: | #x11EB ! 3671: | #x11F0 ! 3672: | #x11F9 ! 3673: | [#x1E00-#x1E9B] ! 3674: | [#x1EA0-#x1EF9] ! 3675: | [#x1F00-#x1F15] ! 3676: | [#x1F18-#x1F1D] ! 3677: | [#x1F20-#x1F45] ! 3678: | [#x1F48-#x1F4D] ! 3679: | [#x1F50-#x1F57] ! 3680: | #x1F59 ! 3681: | #x1F5B ! 3682: | #x1F5D ! 3683: | [#x1F5F-#x1F7D] ! 3684: | [#x1F80-#x1FB4] ! 3685: | [#x1FB6-#x1FBC] ! 3686: | #x1FBE ! 3687: | [#x1FC2-#x1FC4] ! 3688: | [#x1FC6-#x1FCC] ! 3689: | [#x1FD0-#x1FD3] ! 3690: | [#x1FD6-#x1FDB] ! 3691: | [#x1FE0-#x1FEC] ! 3692: | [#x1FF2-#x1FF4] ! 3693: | [#x1FF6-#x1FFC] ! 3694: | #x2126 ! 3695: | [#x212A-#x212B] ! 3696: | #x212E ! 3697: | [#x2180-#x2182] ! 3698: | [#x3041-#x3094] ! 3699: | [#x30A1-#x30FA] ! 3700: | [#x3105-#x312C] ! 3701: | [#xAC00-#xD7A3] ! 3702: </rhs></prod> ! 3703: <prod id='NT-Ideographic'><lhs>Ideographic</lhs> ! 3704: <rhs>[#x4E00-#x9FA5] ! 3705: | #x3007 ! 3706: | [#x3021-#x3029] ! 3707: </rhs></prod> ! 3708: <prod id='NT-CombiningChar'><lhs>CombiningChar</lhs> ! 3709: <rhs>[#x0300-#x0345] ! 3710: | [#x0360-#x0361] ! 3711: | [#x0483-#x0486] ! 3712: | [#x0591-#x05A1] ! 3713: | [#x05A3-#x05B9] ! 3714: | [#x05BB-#x05BD] ! 3715: | #x05BF ! 3716: | [#x05C1-#x05C2] ! 3717: | #x05C4 ! 3718: | [#x064B-#x0652] ! 3719: | #x0670 ! 3720: | [#x06D6-#x06DC] ! 3721: | [#x06DD-#x06DF] ! 3722: | [#x06E0-#x06E4] ! 3723: | [#x06E7-#x06E8] ! 3724: | [#x06EA-#x06ED] ! 3725: | [#x0901-#x0903] ! 3726: | #x093C ! 3727: | [#x093E-#x094C] ! 3728: | #x094D ! 3729: | [#x0951-#x0954] ! 3730: | [#x0962-#x0963] ! 3731: | [#x0981-#x0983] ! 3732: | #x09BC ! 3733: | #x09BE ! 3734: | #x09BF ! 3735: | [#x09C0-#x09C4] ! 3736: | [#x09C7-#x09C8] ! 3737: | [#x09CB-#x09CD] ! 3738: | #x09D7 ! 3739: | [#x09E2-#x09E3] ! 3740: | #x0A02 ! 3741: | #x0A3C ! 3742: | #x0A3E ! 3743: | #x0A3F ! 3744: | [#x0A40-#x0A42] ! 3745: | [#x0A47-#x0A48] ! 3746: | [#x0A4B-#x0A4D] ! 3747: | [#x0A70-#x0A71] ! 3748: | [#x0A81-#x0A83] ! 3749: | #x0ABC ! 3750: | [#x0ABE-#x0AC5] ! 3751: | [#x0AC7-#x0AC9] ! 3752: | [#x0ACB-#x0ACD] ! 3753: | [#x0B01-#x0B03] ! 3754: | #x0B3C ! 3755: | [#x0B3E-#x0B43] ! 3756: | [#x0B47-#x0B48] ! 3757: | [#x0B4B-#x0B4D] ! 3758: | [#x0B56-#x0B57] ! 3759: | [#x0B82-#x0B83] ! 3760: | [#x0BBE-#x0BC2] ! 3761: | [#x0BC6-#x0BC8] ! 3762: | [#x0BCA-#x0BCD] ! 3763: | #x0BD7 ! 3764: | [#x0C01-#x0C03] ! 3765: | [#x0C3E-#x0C44] ! 3766: | [#x0C46-#x0C48] ! 3767: | [#x0C4A-#x0C4D] ! 3768: | [#x0C55-#x0C56] ! 3769: | [#x0C82-#x0C83] ! 3770: | [#x0CBE-#x0CC4] ! 3771: | [#x0CC6-#x0CC8] ! 3772: | [#x0CCA-#x0CCD] ! 3773: | [#x0CD5-#x0CD6] ! 3774: | [#x0D02-#x0D03] ! 3775: | [#x0D3E-#x0D43] ! 3776: | [#x0D46-#x0D48] ! 3777: | [#x0D4A-#x0D4D] ! 3778: | #x0D57 ! 3779: | #x0E31 ! 3780: | [#x0E34-#x0E3A] ! 3781: | [#x0E47-#x0E4E] ! 3782: | #x0EB1 ! 3783: | [#x0EB4-#x0EB9] ! 3784: | [#x0EBB-#x0EBC] ! 3785: | [#x0EC8-#x0ECD] ! 3786: | [#x0F18-#x0F19] ! 3787: | #x0F35 ! 3788: | #x0F37 ! 3789: | #x0F39 ! 3790: | #x0F3E ! 3791: | #x0F3F ! 3792: | [#x0F71-#x0F84] ! 3793: | [#x0F86-#x0F8B] ! 3794: | [#x0F90-#x0F95] ! 3795: | #x0F97 ! 3796: | [#x0F99-#x0FAD] ! 3797: | [#x0FB1-#x0FB7] ! 3798: | #x0FB9 ! 3799: | [#x20D0-#x20DC] ! 3800: | #x20E1 ! 3801: | [#x302A-#x302F] ! 3802: | #x3099 ! 3803: | #x309A ! 3804: </rhs></prod> ! 3805: <prod id='NT-Digit'><lhs>Digit</lhs> ! 3806: <rhs>[#x0030-#x0039] ! 3807: | [#x0660-#x0669] ! 3808: | [#x06F0-#x06F9] ! 3809: | [#x0966-#x096F] ! 3810: | [#x09E6-#x09EF] ! 3811: | [#x0A66-#x0A6F] ! 3812: | [#x0AE6-#x0AEF] ! 3813: | [#x0B66-#x0B6F] ! 3814: | [#x0BE7-#x0BEF] ! 3815: | [#x0C66-#x0C6F] ! 3816: | [#x0CE6-#x0CEF] ! 3817: | [#x0D66-#x0D6F] ! 3818: | [#x0E50-#x0E59] ! 3819: | [#x0ED0-#x0ED9] ! 3820: | [#x0F20-#x0F29] ! 3821: </rhs></prod> ! 3822: <prod id='NT-Extender'><lhs>Extender</lhs> ! 3823: <rhs>#x00B7 ! 3824: | #x02D0 ! 3825: | #x02D1 ! 3826: | #x0387 ! 3827: | #x0640 ! 3828: | #x0E46 ! 3829: | #x0EC6 ! 3830: | #x3005 ! 3831: | [#x3031-#x3035] ! 3832: | [#x309D-#x309E] ! 3833: | [#x30FC-#x30FE] ! 3834: </rhs></prod> ! 3835: ! 3836: </prodgroup> ! 3837: </scrap> ! 3838: </p> ! 3839: <p>The character classes defined here can be derived from the ! 3840: Unicode character database as follows: ! 3841: <ulist> ! 3842: <item> ! 3843: <p>Name start characters must have one of the categories Ll, Lu, ! 3844: Lo, Lt, Nl.</p> ! 3845: </item> ! 3846: <item> ! 3847: <p>Name characters other than Name-start characters ! 3848: must have one of the categories Mc, Me, Mn, Lm, or Nd.</p> ! 3849: </item> ! 3850: <item> ! 3851: <p>Characters in the compatibility area (i.e. with character code ! 3852: greater than #xF900 and less than #xFFFE) are not allowed in XML ! 3853: names.</p> ! 3854: </item> ! 3855: <item> ! 3856: <p>Characters which have a font or compatibility decomposition (i.e. those ! 3857: with a "compatibility formatting tag" in field 5 of the database -- ! 3858: marked by field 5 beginning with a "<") are not allowed.</p> ! 3859: </item> ! 3860: <item> ! 3861: <p>The following characters are treated as name-start characters ! 3862: rather than name characters, because the property file classifies ! 3863: them as Alphabetic: [#x02BB-#x02C1], #x0559, #x06E5, #x06E6.</p> ! 3864: </item> ! 3865: <item> ! 3866: <p>Characters #x20DD-#x20E0 are excluded (in accordance with ! 3867: Unicode, section 5.14).</p> ! 3868: </item> ! 3869: <item> ! 3870: <p>Character #x00B7 is classified as an extender, because the ! 3871: property list so identifies it.</p> ! 3872: </item> ! 3873: <item> ! 3874: <p>Character #x0387 is added as a name character, because #x00B7 ! 3875: is its canonical equivalent.</p> ! 3876: </item> ! 3877: <item> ! 3878: <p>Characters ':' and '_' are allowed as name-start characters.</p> ! 3879: </item> ! 3880: <item> ! 3881: <p>Characters '-' and '.' are allowed as name characters.</p> ! 3882: </item> ! 3883: </ulist> ! 3884: </p> ! 3885: </div1> ! 3886: <inform-div1 id="sec-xml-and-sgml"> ! 3887: <head>XML and SGML</head> ! 3888: ! 3889: <p>XML is designed to be a subset of SGML, in that every ! 3890: <termref def="dt-valid">valid</termref> XML document should also be a ! 3891: conformant SGML document. ! 3892: For a detailed comparison of the additional restrictions that XML places on ! 3893: documents beyond those of SGML, see <bibref ref='Clark'/>. ! 3894: </p> ! 3895: </inform-div1> ! 3896: <inform-div1 id="sec-entexpand"> ! 3897: <head>Expansion of Entity and Character References</head> ! 3898: <p>This appendix contains some examples illustrating the ! 3899: sequence of entity- and character-reference recognition and ! 3900: expansion, as specified in <specref ref='entproc'/>.</p> ! 3901: <p> ! 3902: If the DTD contains the declaration ! 3903: <eg><![CDATA[<!ENTITY example "<p>An ampersand (&#38;) may be escaped ! 3904: numerically (&#38;#38;) or with a general entity ! 3905: (&amp;).</p>" > ! 3906: ]]></eg> ! 3907: then the XML processor will recognize the character references ! 3908: when it parses the entity declaration, and resolve them before ! 3909: storing the following string as the ! 3910: value of the entity "<code>example</code>": ! 3911: <eg><![CDATA[<p>An ampersand (&) may be escaped ! 3912: numerically (&#38;) or with a general entity ! 3913: (&amp;).</p> ! 3914: ]]></eg> ! 3915: A reference in the document to "<code>&example;</code>" ! 3916: will cause the text to be reparsed, at which time the ! 3917: start- and end-tags of the "<code>p</code>" element will be recognized ! 3918: and the three references will be recognized and expanded, ! 3919: resulting in a "<code>p</code>" element with the following content ! 3920: (all data, no delimiters or markup): ! 3921: <eg><![CDATA[An ampersand (&) may be escaped ! 3922: numerically (&) or with a general entity ! 3923: (&). ! 3924: ]]></eg> ! 3925: </p> ! 3926: <p>A more complex example will illustrate the rules and their ! 3927: effects fully. In the following example, the line numbers are ! 3928: solely for reference. ! 3929: <eg><![CDATA[1 <?xml version='1.0'?> ! 3930: 2 <!DOCTYPE test [ ! 3931: 3 <!ELEMENT test (#PCDATA) > ! 3932: 4 <!ENTITY % xx '%zz;'> ! 3933: 5 <!ENTITY % zz '<!ENTITY tricky "error-prone" >' > ! 3934: 6 %xx; ! 3935: 7 ]> ! 3936: 8 <test>This sample shows a &tricky; method.</test> ! 3937: ]]></eg> ! 3938: This produces the following: ! 3939: <ulist spacing="compact"> ! 3940: <item><p>in line 4, the reference to character 37 is expanded immediately, ! 3941: and the parameter entity "<code>xx</code>" is stored in the symbol ! 3942: table with the value "<code>%zz;</code>". Since the replacement text ! 3943: is not rescanned, the reference to parameter entity "<code>zz</code>" ! 3944: is not recognized. (And it would be an error if it were, since ! 3945: "<code>zz</code>" is not yet declared.)</p></item> ! 3946: <item><p>in line 5, the character reference "<code>&#60;</code>" is ! 3947: expanded immediately and the parameter entity "<code>zz</code>" is ! 3948: stored with the replacement text ! 3949: "<code><!ENTITY tricky "error-prone" ></code>", ! 3950: which is a well-formed entity declaration.</p></item> ! 3951: <item><p>in line 6, the reference to "<code>xx</code>" is recognized, ! 3952: and the replacement text of "<code>xx</code>" (namely ! 3953: "<code>%zz;</code>") is parsed. The reference to "<code>zz</code>" ! 3954: is recognized in its turn, and its replacement text ! 3955: ("<code><!ENTITY tricky "error-prone" ></code>") is parsed. ! 3956: The general entity "<code>tricky</code>" has now been ! 3957: declared, with the replacement text "<code>error-prone</code>".</p></item> ! 3958: <item><p> ! 3959: in line 8, the reference to the general entity "<code>tricky</code>" is ! 3960: recognized, and it is expanded, so the full content of the ! 3961: "<code>test</code>" element is the self-describing (and ungrammatical) string ! 3962: <emph>This sample shows a error-prone method.</emph> ! 3963: </p></item> ! 3964: </ulist> ! 3965: </p> ! 3966: </inform-div1> ! 3967: <inform-div1 id="determinism"> ! 3968: <head>Deterministic Content Models</head> ! 3969: <p><termref def='dt-compat'>For compatibility</termref>, it is ! 3970: required ! 3971: that content models in element type declarations be deterministic. ! 3972: </p> ! 3973: <!-- FINAL EDIT: WebSGML allows ambiguity? --> ! 3974: <p>SGML ! 3975: requires deterministic content models (it calls them ! 3976: "unambiguous"); XML processors built using SGML systems may ! 3977: flag non-deterministic content models as errors.</p> ! 3978: <p>For example, the content model <code>((b, c) | (b, d))</code> is ! 3979: non-deterministic, because given an initial <code>b</code> the parser ! 3980: cannot know which <code>b</code> in the model is being matched without ! 3981: looking ahead to see which element follows the <code>b</code>. ! 3982: In this case, the two references to ! 3983: <code>b</code> can be collapsed ! 3984: into a single reference, making the model read ! 3985: <code>(b, (c | d))</code>. An initial <code>b</code> now clearly ! 3986: matches only a single name in the content model. The parser doesn't ! 3987: need to look ahead to see what follows; either <code>c</code> or ! 3988: <code>d</code> would be accepted.</p> ! 3989: <p>More formally: a finite state automaton may be constructed from the ! 3990: content model using the standard algorithms, e.g. algorithm 3.5 ! 3991: in section 3.9 ! 3992: of Aho, Sethi, and Ullman <bibref ref='Aho'/>. ! 3993: In many such algorithms, a follow set is constructed for each ! 3994: position in the regular expression (i.e., each leaf ! 3995: node in the ! 3996: syntax tree for the regular expression); ! 3997: if any position has a follow set in which ! 3998: more than one following position is ! 3999: labeled with the same element type name, ! 4000: then the content model is in error ! 4001: and may be reported as an error. ! 4002: </p> ! 4003: <p>Algorithms exist which allow many but not all non-deterministic ! 4004: content models to be reduced automatically to equivalent deterministic ! 4005: models; see Brüggemann-Klein 1991 <bibref ref='ABK'/>.</p> ! 4006: </inform-div1> ! 4007: <inform-div1 id="sec-guessing"> ! 4008: <head>Autodetection of Character Encodings</head> ! 4009: <p>The XML encoding declaration functions as an internal label on each ! 4010: entity, indicating which character encoding is in use. Before an XML ! 4011: processor can read the internal label, however, it apparently has to ! 4012: know what character encoding is in use—which is what the internal label ! 4013: is trying to indicate. In the general case, this is a hopeless ! 4014: situation. It is not entirely hopeless in XML, however, because XML ! 4015: limits the general case in two ways: each implementation is assumed ! 4016: to support only a finite set of character encodings, and the XML ! 4017: encoding declaration is restricted in position and content in order to ! 4018: make it feasible to autodetect the character encoding in use in each ! 4019: entity in normal cases. Also, in many cases other sources of information ! 4020: are available in addition to the XML data stream itself. ! 4021: Two cases may be distinguished, ! 4022: depending on whether the XML entity is presented to the ! 4023: processor without, or with, any accompanying ! 4024: (external) information. We consider the first case first. ! 4025: </p> ! 4026: <p> ! 4027: Because each XML entity not in UTF-8 or UTF-16 format <emph>must</emph> ! 4028: begin with an XML encoding declaration, in which the first characters ! 4029: must be '<code><?xml</code>', any conforming processor can detect, ! 4030: after two to four octets of input, which of the following cases apply. ! 4031: In reading this list, it may help to know that in UCS-4, '<' is ! 4032: "<code>#x0000003C</code>" and '?' is "<code>#x0000003F</code>", and the Byte ! 4033: Order Mark required of UTF-16 data streams is "<code>#xFEFF</code>".</p> ! 4034: <p> ! 4035: <ulist> ! 4036: <item> ! 4037: <p><code>00 00 00 3C</code>: UCS-4, big-endian machine (1234 order)</p> ! 4038: </item> ! 4039: <item> ! 4040: <p><code>3C 00 00 00</code>: UCS-4, little-endian machine (4321 order)</p> ! 4041: </item> ! 4042: <item> ! 4043: <p><code>00 00 3C 00</code>: UCS-4, unusual octet order (2143)</p> ! 4044: </item> ! 4045: <item> ! 4046: <p><code>00 3C 00 00</code>: UCS-4, unusual octet order (3412)</p> ! 4047: </item> ! 4048: <item> ! 4049: <p><code>FE FF</code>: UTF-16, big-endian</p> ! 4050: </item> ! 4051: <item> ! 4052: <p><code>FF FE</code>: UTF-16, little-endian</p> ! 4053: </item> ! 4054: <item> ! 4055: <p><code>00 3C 00 3F</code>: UTF-16, big-endian, no Byte Order Mark ! 4056: (and thus, strictly speaking, in error)</p> ! 4057: </item> ! 4058: <item> ! 4059: <p><code>3C 00 3F 00</code>: UTF-16, little-endian, no Byte Order Mark ! 4060: (and thus, strictly speaking, in error)</p> ! 4061: </item> ! 4062: <item> ! 4063: <p><code>3C 3F 78 6D</code>: UTF-8, ISO 646, ASCII, some part of ISO 8859, ! 4064: Shift-JIS, EUC, or any other 7-bit, 8-bit, or mixed-width encoding ! 4065: which ensures that the characters of ASCII have their normal positions, ! 4066: width, ! 4067: and values; the actual encoding declaration must be read to ! 4068: detect which of these applies, but since all of these encodings ! 4069: use the same bit patterns for the ASCII characters, the encoding ! 4070: declaration itself may be read reliably ! 4071: </p> ! 4072: </item> ! 4073: <item> ! 4074: <p><code>4C 6F A7 94</code>: EBCDIC (in some flavor; the full ! 4075: encoding declaration must be read to tell which code page is in ! 4076: use)</p> ! 4077: </item> ! 4078: <item> ! 4079: <p>other: UTF-8 without an encoding declaration, or else ! 4080: the data stream is corrupt, fragmentary, or enclosed in ! 4081: a wrapper of some kind</p> ! 4082: </item> ! 4083: </ulist> ! 4084: </p> ! 4085: <p> ! 4086: This level of autodetection is enough to read the XML encoding ! 4087: declaration and parse the character-encoding identifier, which is ! 4088: still necessary to distinguish the individual members of each family ! 4089: of encodings (e.g. to tell UTF-8 from 8859, and the parts of 8859 ! 4090: from each other, or to distinguish the specific EBCDIC code page in ! 4091: use, and so on). ! 4092: </p> ! 4093: <p> ! 4094: Because the contents of the encoding declaration are restricted to ! 4095: ASCII characters, a processor can reliably read the entire encoding ! 4096: declaration as soon as it has detected which family of encodings is in ! 4097: use. Since in practice, all widely used character encodings fall into ! 4098: one of the categories above, the XML encoding declaration allows ! 4099: reasonably reliable in-band labeling of character encodings, even when ! 4100: external sources of information at the operating-system or ! 4101: transport-protocol level are unreliable. ! 4102: </p> ! 4103: <p> ! 4104: Once the processor has detected the character encoding in use, it can ! 4105: act appropriately, whether by invoking a separate input routine for ! 4106: each case, or by calling the proper conversion function on each ! 4107: character of input. ! 4108: </p> ! 4109: <p> ! 4110: Like any self-labeling system, the XML encoding declaration will not ! 4111: work if any software changes the entity's character set or encoding ! 4112: without updating the encoding declaration. Implementors of ! 4113: character-encoding routines should be careful to ensure the accuracy ! 4114: of the internal and external information used to label the entity. ! 4115: </p> ! 4116: <p>The second possible case occurs when the XML entity is accompanied ! 4117: by encoding information, as in some file systems and some network ! 4118: protocols. ! 4119: When multiple sources of information are available, ! 4120: ! 4121: their relative ! 4122: priority and the preferred method of handling conflict should be ! 4123: specified as part of the higher-level protocol used to deliver XML. ! 4124: Rules for the relative priority of the internal label and the ! 4125: MIME-type label in an external header, for example, should be part of the ! 4126: RFC document defining the text/xml and application/xml MIME types. In ! 4127: the interests of interoperability, however, the following rules ! 4128: are recommended. ! 4129: <ulist> ! 4130: <item><p>If an XML entity is in a file, the Byte-Order Mark ! 4131: and encoding-declaration PI are used (if present) to determine the ! 4132: character encoding. All other heuristics and sources of information ! 4133: are solely for error recovery. ! 4134: </p></item> ! 4135: <item><p>If an XML entity is delivered with a ! 4136: MIME type of text/xml, then the <code>charset</code> parameter ! 4137: on the MIME type determines the ! 4138: character encoding method; all other heuristics and sources of ! 4139: information are solely for error recovery. ! 4140: </p></item> ! 4141: <item><p>If an XML entity is delivered ! 4142: with a ! 4143: MIME type of application/xml, then the Byte-Order Mark and ! 4144: encoding-declaration PI are used (if present) to determine the ! 4145: character encoding. All other heuristics and sources of ! 4146: information are solely for error recovery. ! 4147: </p></item> ! 4148: </ulist> ! 4149: These rules apply only in the absence of protocol-level documentation; ! 4150: in particular, when the MIME types text/xml and application/xml are ! 4151: defined, the recommendations of the relevant RFC will supersede ! 4152: these rules. ! 4153: </p> ! 4154: ! 4155: </inform-div1> ! 4156: ! 4157: <inform-div1 id="sec-xml-wg"> ! 4158: <head>W3C XML Working Group</head> ! 4159: ! 4160: <p>This specification was prepared and approved for publication by the ! 4161: W3C XML Working Group (WG). WG approval of this specification does ! 4162: not necessarily imply that all WG members voted for its approval. ! 4163: The current and former members of the XML WG are:</p> ! 4164: ! 4165: <orglist> ! 4166: <member><name>Jon Bosak, Sun</name><role>Chair</role></member> ! 4167: <member><name>James Clark</name><role>Technical Lead</role></member> ! 4168: <member><name>Tim Bray, Textuality and Netscape</name><role>XML Co-editor</role></member> ! 4169: <member><name>Jean Paoli, Microsoft</name><role>XML Co-editor</role></member> ! 4170: <member><name>C. M. Sperberg-McQueen, U. of Ill.</name><role>XML ! 4171: Co-editor</role></member> ! 4172: <member><name>Dan Connolly, W3C</name><role>W3C Liaison</role></member> ! 4173: <member><name>Paula Angerstein, Texcel</name></member> ! 4174: <member><name>Steve DeRose, INSO</name></member> ! 4175: <member><name>Dave Hollander, HP</name></member> ! 4176: <member><name>Eliot Kimber, ISOGEN</name></member> ! 4177: <member><name>Eve Maler, ArborText</name></member> ! 4178: <member><name>Tom Magliery, NCSA</name></member> ! 4179: <member><name>Murray Maloney, Muzmo and Grif</name></member> ! 4180: <member><name>Makoto Murata, Fuji Xerox Information Systems</name></member> ! 4181: <member><name>Joel Nava, Adobe</name></member> ! 4182: <member><name>Conleth O'Connell, Vignette</name></member> ! 4183: <member><name>Peter Sharpe, SoftQuad</name></member> ! 4184: <member><name>John Tigue, DataChannel</name></member> ! 4185: </orglist> ! 4186: ! 4187: </inform-div1> ! 4188: </back> ! 4189: </spec> ! 4190: <!-- Keep this comment at the end of the file ! 4191: Local variables: ! 4192: mode: sgml ! 4193: sgml-default-dtd-file:"~/sgml/spec.ced" ! 4194: sgml-omittag:t ! 4195: sgml-shorttag:t ! 4196: End: ! 4197: -->