Annotation of embedaddon/libxml2/result/valid/REC-xml-19980210.xml, revision 1.1
1.1 ! misho 1: <?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
! 2: <!DOCTYPE spec SYSTEM "dtds/spec.dtd" [
! 3: <!-- LAST TOUCHED BY: Tim Bray, 8 February 1997 --><!-- The words 'FINAL EDIT' in comments mark places where changes
! 4: need to be made after approval of the document by the ERB, before
! 5: publication. --><!ENTITY XML.version "1.0">
! 6: <!ENTITY doc.date "10 February 1998">
! 7: <!ENTITY iso6.doc.date "19980210">
! 8: <!ENTITY w3c.doc.date "02-Feb-1998">
! 9: <!ENTITY draft.day "10">
! 10: <!ENTITY draft.month "February">
! 11: <!ENTITY draft.year "1998">
! 12: <!ENTITY WebSGML "WebSGML Adaptations Annex to ISO 8879">
! 13: <!ENTITY lt "<">
! 14: <!ENTITY gt ">">
! 15: <!ENTITY xmlpio "'<?xml'">
! 16: <!ENTITY pic "'?>'">
! 17: <!ENTITY br "\n">
! 18: <!ENTITY cellback "#c0d9c0">
! 19: <!ENTITY mdash "--">
! 20: <!-- —, but nsgmls doesn't grok hex --><!ENTITY com "--">
! 21: <!ENTITY como "--">
! 22: <!ENTITY comc "--">
! 23: <!ENTITY hcro "&#x">
! 24: <!-- <!ENTITY nbsp " "> --><!ENTITY nbsp " ">
! 25: <!ENTITY magicents "<code>amp</code>,
! 26: <code>lt</code>,
! 27: <code>gt</code>,
! 28: <code>apos</code>,
! 29: <code>quot</code>">
! 30: <!-- audience and distribution status: for use at publication time --><!ENTITY doc.audience "public review and discussion">
! 31: <!ENTITY doc.distribution "may be distributed freely, as long as
! 32: all text and legal notices remain intact">
! 33: ]>
! 34: <!-- for Panorama *-->
! 35: <?VERBATIM "eg" ?>
! 36: <spec>
! 37: <header>
! 38: <title>Extensible Markup Language (XML) 1.0</title>
! 39: <version/>
! 40: <w3c-designation>REC-xml-&iso6.doc.date;</w3c-designation>
! 41: <w3c-doctype>W3C Recommendation</w3c-doctype>
! 42: <pubdate><day>&draft.day;</day><month>&draft.month;</month><year>&draft.year;</year></pubdate>
! 43:
! 44: <publoc>
! 45: <loc href="http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;">
! 46: http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;</loc>
! 47: <loc href="http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.xml">
! 48: http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.xml</loc>
! 49: <loc href="http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.html">
! 50: http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.html</loc>
! 51: <loc href="http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.pdf">
! 52: http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.pdf</loc>
! 53: <loc href="http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.ps">
! 54: http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.ps</loc>
! 55: </publoc>
! 56: <latestloc>
! 57: <loc href="http://www.w3.org/TR/REC-xml">
! 58: http://www.w3.org/TR/REC-xml</loc>
! 59: </latestloc>
! 60: <prevlocs>
! 61: <loc href="http://www.w3.org/TR/PR-xml-971208">
! 62: http://www.w3.org/TR/PR-xml-971208</loc>
! 63: <!--
! 64: <loc href='http://www.w3.org/TR/WD-xml-961114'>
! 65: http://www.w3.org/TR/WD-xml-961114</loc>
! 66: <loc href='http://www.w3.org/TR/WD-xml-lang-970331'>
! 67: http://www.w3.org/TR/WD-xml-lang-970331</loc>
! 68: <loc href='http://www.w3.org/TR/WD-xml-lang-970630'>
! 69: http://www.w3.org/TR/WD-xml-lang-970630</loc>
! 70: <loc href='http://www.w3.org/TR/WD-xml-970807'>
! 71: http://www.w3.org/TR/WD-xml-970807</loc>
! 72: <loc href='http://www.w3.org/TR/WD-xml-971117'>
! 73: http://www.w3.org/TR/WD-xml-971117</loc>-->
! 74: </prevlocs>
! 75: <authlist>
! 76: <author><name>Tim Bray</name>
! 77: <affiliation>Textuality and Netscape</affiliation>
! 78: <email href="mailto:tbray@textuality.com">tbray@textuality.com</email></author>
! 79: <author><name>Jean Paoli</name>
! 80: <affiliation>Microsoft</affiliation>
! 81: <email href="mailto:jeanpa@microsoft.com">jeanpa@microsoft.com</email></author>
! 82: <author><name>C. M. Sperberg-McQueen</name>
! 83: <affiliation>University of Illinois at Chicago</affiliation>
! 84: <email href="mailto:cmsmcq@uic.edu">cmsmcq@uic.edu</email></author>
! 85: </authlist>
! 86: <abstract>
! 87: <p>The Extensible Markup Language (XML) is a subset of
! 88: SGML that is completely described in this document. Its goal is to
! 89: enable generic SGML to be served, received, and processed on the Web
! 90: in the way that is now possible with HTML. XML has been designed for
! 91: ease of implementation and for interoperability with both SGML and
! 92: HTML.</p>
! 93: </abstract>
! 94: <status>
! 95: <p>This document has been reviewed by W3C Members and
! 96: other interested parties and has been endorsed by the
! 97: Director as a W3C Recommendation. It is a stable
! 98: document and may be used as reference material or cited
! 99: as a normative reference from another document. W3C's
! 100: role in making the Recommendation is to draw attention
! 101: to the specification and to promote its widespread
! 102: deployment. This enhances the functionality and
! 103: interoperability of the Web.</p>
! 104: <p>
! 105: This document specifies a syntax created by subsetting an existing,
! 106: widely used international text processing standard (Standard
! 107: Generalized Markup Language, ISO 8879:1986(E) as amended and
! 108: corrected) for use on the World Wide Web. It is a product of the W3C
! 109: XML Activity, details of which can be found at <loc href="http://www.w3.org/XML">http://www.w3.org/XML</loc>. A list of
! 110: current W3C Recommendations and other technical documents can be found
! 111: at <loc href="http://www.w3.org/TR">http://www.w3.org/TR</loc>.
! 112: </p>
! 113: <p>This specification uses the term URI, which is defined by <bibref ref="Berners-Lee"/>, a work in progress expected to update <bibref ref="RFC1738"/> and <bibref ref="RFC1808"/>.
! 114: </p>
! 115: <p>The list of known errors in this specification is
! 116: available at
! 117: <loc href="http://www.w3.org/XML/xml-19980210-errata">http://www.w3.org/XML/xml-19980210-errata</loc>.</p>
! 118: <p>Please report errors in this document to
! 119: <loc href="mailto:xml-editor@w3.org">xml-editor@w3.org</loc>.
! 120: </p>
! 121: </status>
! 122:
! 123:
! 124: <pubstmt>
! 125: <p>Chicago, Vancouver, Mountain View, et al.:
! 126: World-Wide Web Consortium, XML Working Group, 1996, 1997.</p>
! 127: </pubstmt>
! 128: <sourcedesc>
! 129: <p>Created in electronic form.</p>
! 130: </sourcedesc>
! 131: <langusage>
! 132: <language id="EN">English</language>
! 133: <language id="ebnf">Extended Backus-Naur Form (formal grammar)</language>
! 134: </langusage>
! 135: <revisiondesc>
! 136: <slist>
! 137: <sitem>1997-12-03 : CMSMcQ : yet further changes</sitem>
! 138: <sitem>1997-12-02 : TB : further changes (see TB to XML WG,
! 139: 2 December 1997)</sitem>
! 140: <sitem>1997-12-02 : CMSMcQ : deal with as many corrections and
! 141: comments from the proofreaders as possible:
! 142: entify hard-coded document date in pubdate element,
! 143: change expansion of entity WebSGML,
! 144: update status description as per Dan Connolly (am not sure
! 145: about refernece to Berners-Lee et al.),
! 146: add 'The' to abstract as per WG decision,
! 147: move Relationship to Existing Standards to back matter and
! 148: combine with References,
! 149: re-order back matter so normative appendices come first,
! 150: re-tag back matter so informative appendices are tagged informdiv1,
! 151: remove XXX XXX from list of 'normative' specs in prose,
! 152: move some references from Other References to Normative References,
! 153: add RFC 1738, 1808, and 2141 to Other References (they are not
! 154: normative since we do not require the processor to enforce any
! 155: rules based on them),
! 156: add reference to 'Fielding draft' (Berners-Lee et al.),
! 157: move notation section to end of body,
! 158: drop URIchar non-terminal and use SkipLit instead,
! 159: lose stray reference to defunct nonterminal 'markupdecls',
! 160: move reference to Aho et al. into appendix (Tim's right),
! 161: add prose note saying that hash marks and fragment identifiers are
! 162: NOT part of the URI formally speaking, and are NOT legal in
! 163: system identifiers (processor 'may' signal an error).
! 164: Work through:
! 165: Tim Bray reacting to James Clark,
! 166: Tim Bray on his own,
! 167: Eve Maler,
! 168:
! 169: NOT DONE YET:
! 170: change binary / text to unparsed / parsed.
! 171: handle James's suggestion about < in attriubte values
! 172: uppercase hex characters,
! 173: namechar list,
! 174: </sitem>
! 175: <sitem>1997-12-01 : JB : add some column-width parameters</sitem>
! 176: <sitem>1997-12-01 : CMSMcQ : begin round of changes to incorporate
! 177: recent WG decisions and other corrections:
! 178: binding sources of character encoding info (27 Aug / 3 Sept),
! 179: correct wording of Faust quotation (restore dropped line),
! 180: drop SDD from EncodingDecl,
! 181: change text at version number 1.0,
! 182: drop misleading (wrong!) sentence about ignorables and extenders,
! 183: modify definition of PCData to make bar on msc grammatical,
! 184: change grammar's handling of internal subset (drop non-terminal markupdecls),
! 185: change definition of includeSect to allow conditional sections,
! 186: add integral-declaration constraint on internal subset,
! 187: drop misleading / dangerous sentence about relationship of
! 188: entities with system storage objects,
! 189: change table body tag to htbody as per EM change to DTD,
! 190: add rule about space normalization in public identifiers,
! 191: add description of how to generate our name-space rules from
! 192: Unicode character database (needs further work!).
! 193: </sitem>
! 194: <sitem>1997-10-08 : TB : Removed %-constructs again, new rules
! 195: for PE appearance.</sitem>
! 196: <sitem>1997-10-01 : TB : Case-sensitive markup; cleaned up
! 197: element-type defs, lotsa little edits for style</sitem>
! 198: <sitem>1997-09-25 : TB : Change to elm's new DTD, with
! 199: substantial detail cleanup as a side-effect</sitem>
! 200: <sitem>1997-07-24 : CMSMcQ : correct error (lost *) in definition
! 201: of ignoreSectContents (thanks to Makoto Murata)</sitem>
! 202: <sitem>Allow all empty elements to have end-tags, consistent with
! 203: SGML TC (as per JJC).</sitem>
! 204: <sitem>1997-07-23 : CMSMcQ : pre-emptive strike on pending corrections:
! 205: introduce the term 'empty-element tag', note that all empty elements
! 206: may use it, and elements declared EMPTY must use it.
! 207: Add WFC requiring encoding decl to come first in an entity.
! 208: Redefine notations to point to PIs as well as binary entities.
! 209: Change autodetection table by removing bytes 3 and 4 from
! 210: examples with Byte Order Mark.
! 211: Add content model as a term and clarify that it applies to both
! 212: mixed and element content.
! 213: </sitem>
! 214: <sitem>1997-06-30 : CMSMcQ : change date, some cosmetic changes,
! 215: changes to productions for choice, seq, Mixed, NotationType,
! 216: Enumeration. Follow James Clark's suggestion and prohibit
! 217: conditional sections in internal subset. TO DO: simplify
! 218: production for ignored sections as a result, since we don't
! 219: need to worry about parsers which don't expand PErefs finding
! 220: a conditional section.</sitem>
! 221: <sitem>1997-06-29 : TB : various edits</sitem>
! 222: <sitem>1997-06-29 : CMSMcQ : further changes:
! 223: Suppress old FINAL EDIT comments and some dead material.
! 224: Revise occurrences of % in grammar to exploit Henry Thompson's pun,
! 225: especially markupdecl and attdef.
! 226: Remove RMD requirement relating to element content (?).
! 227: </sitem>
! 228: <sitem>1997-06-28 : CMSMcQ : Various changes for 1 July draft:
! 229: Add text for draconian error handling (introduce
! 230: the term Fatal Error).
! 231: RE deleta est (changing wording from
! 232: original announcement to restrict the requirement to validating
! 233: parsers).
! 234: Tag definition of validating processor and link to it.
! 235: Add colon as name character.
! 236: Change def of %operator.
! 237: Change standard definitions of lt, gt, amp.
! 238: Strip leading zeros from #x00nn forms.</sitem>
! 239: <sitem>1997-04-02 : CMSMcQ : final corrections of editorial errors
! 240: found in last night's proofreading. Reverse course once more on
! 241: well-formed: Webster's Second hyphenates it, and that's enough
! 242: for me.</sitem>
! 243: <sitem>1997-04-01 : CMSMcQ : corrections from JJC, EM, HT, and self</sitem>
! 244: <sitem>1997-03-31 : Tim Bray : many changes</sitem>
! 245: <sitem>1997-03-29 : CMSMcQ : some Henry Thompson (on entity handling),
! 246: some Charles Goldfarb, some ERB decisions (PE handling in miscellaneous
! 247: declarations. Changed Ident element to accept def attribute.
! 248: Allow normalization of Unicode characters. move def of systemliteral
! 249: into section on literals.</sitem>
! 250: <sitem>1997-03-28 : CMSMcQ : make as many corrections as possible, from
! 251: Terry Allen, Norbert Mikula, James Clark, Jon Bosak, Henry Thompson,
! 252: Paul Grosso, and self. Among other things: give in on "well formed"
! 253: (Terry is right), tentatively rename QuotedCData as AttValue
! 254: and Literal as EntityValue to be more informative, since attribute
! 255: values are the <emph>only</emph> place QuotedCData was used, and
! 256: vice versa for entity text and Literal. (I'd call it Entity Text,
! 257: but 8879 uses that name for both internal and external entities.)</sitem>
! 258: <sitem>1997-03-26 : CMSMcQ : resynch the two forks of this draft, reapply
! 259: my changes dated 03-20 and 03-21. Normalize old 'may not' to 'must not'
! 260: except in the one case where it meant 'may or may not'.</sitem>
! 261: <sitem>1997-03-21 : TB : massive changes on plane flight from Chicago
! 262: to Vancouver</sitem>
! 263: <sitem>1997-03-21 : CMSMcQ : correct as many reported errors as possible.
! 264: </sitem>
! 265: <sitem>1997-03-20 : CMSMcQ : correct typos listed in CMSMcQ hand copy of spec.</sitem>
! 266: <sitem>1997-03-20 : CMSMcQ : cosmetic changes preparatory to revision for
! 267: WWW conference April 1997: restore some of the internal entity
! 268: references (e.g. to docdate, etc.), change character xA0 to &nbsp;
! 269: and define nbsp as &#160;, and refill a lot of paragraphs for
! 270: legibility.</sitem>
! 271: <sitem>1996-11-12 : CMSMcQ : revise using Tim's edits:
! 272: Add list type of NUMBERED and change most lists either to
! 273: BULLETS or to NUMBERED.
! 274: Suppress QuotedNames, Names (not used).
! 275: Correct trivial-grammar doc type decl.
! 276: Rename 'marked section' as 'CDATA section' passim.
! 277: Also edits from James Clark:
! 278: Define the set of characters from which [^abc] subtracts.
! 279: Charref should use just [0-9] not Digit.
! 280: Location info needs cleaner treatment: remove? (ERB
! 281: question).
! 282: One example of a PI has wrong pic.
! 283: Clarify discussion of encoding names.
! 284: Encoding failure should lead to unspecified results; don't
! 285: prescribe error recovery.
! 286: Don't require exposure of entity boundaries.
! 287: Ignore white space in element content.
! 288: Reserve entity names of the form u-NNNN.
! 289: Clarify relative URLs.
! 290: And some of my own:
! 291: Correct productions for content model: model cannot
! 292: consist of a name, so "elements ::= cp" is no good.
! 293: </sitem>
! 294: <sitem>1996-11-11 : CMSMcQ : revise for style.
! 295: Add new rhs to entity declaration, for parameter entities.</sitem>
! 296: <sitem>1996-11-10 : CMSMcQ : revise for style.
! 297: Fix / complete section on names, characters.
! 298: Add sections on parameter entities, conditional sections.
! 299: Still to do: Add compatibility note on deterministic content models.
! 300: Finish stylistic revision.</sitem>
! 301: <sitem>1996-10-31 : TB : Add Entity Handling section</sitem>
! 302: <sitem>1996-10-30 : TB : Clean up term & termdef. Slip in
! 303: ERB decision re EMPTY.</sitem>
! 304: <sitem>1996-10-28 : TB : Change DTD. Implement some of Michael's
! 305: suggestions. Change comments back to //. Introduce language for
! 306: XML namespace reservation. Add section on white-space handling.
! 307: Lots more cleanup.</sitem>
! 308: <sitem>1996-10-24 : CMSMcQ : quick tweaks, implement some ERB
! 309: decisions. Characters are not integers. Comments are /* */ not //.
! 310: Add bibliographic refs to 10646, HyTime, Unicode.
! 311: Rename old Cdata as MsData since it's <emph>only</emph> seen
! 312: in marked sections. Call them attribute-value pairs not
! 313: name-value pairs, except once. Internal subset is optional, needs
! 314: '?'. Implied attributes should be signaled to the app, not
! 315: have values supplied by processor.</sitem>
! 316: <sitem>1996-10-16 : TB : track down & excise all DSD references;
! 317: introduce some EBNF for entity declarations.</sitem>
! 318: <sitem>1996-10-?? : TB : consistency check, fix up scraps so
! 319: they all parse, get formatter working, correct a few productions.</sitem>
! 320: <sitem>1996-10-10/11 : CMSMcQ : various maintenance, stylistic, and
! 321: organizational changes:
! 322: Replace a few literals with xmlpio and
! 323: pic entities, to make them consistent and ensure we can change pic
! 324: reliably when the ERB votes.
! 325: Drop paragraph on recognizers from notation section.
! 326: Add match, exact match to terminology.
! 327: Move old 2.2 XML Processors and Apps into intro.
! 328: Mention comments, PIs, and marked sections in discussion of
! 329: delimiter escaping.
! 330: Streamline discussion of doctype decl syntax.
! 331: Drop old section of 'PI syntax' for doctype decl, and add
! 332: section on partial-DTD summary PIs to end of Logical Structures
! 333: section.
! 334: Revise DSD syntax section to use Tim's subset-in-a-PI
! 335: mechanism.</sitem>
! 336: <sitem>1996-10-10 : TB : eliminate name recognizers (and more?)</sitem>
! 337: <sitem>1996-10-09 : CMSMcQ : revise for style, consistency through 2.3
! 338: (Characters)</sitem>
! 339: <sitem>1996-10-09 : CMSMcQ : re-unite everything for convenience,
! 340: at least temporarily, and revise quickly</sitem>
! 341: <sitem>1996-10-08 : TB : first major homogenization pass</sitem>
! 342: <sitem>1996-10-08 : TB : turn "current" attribute on div type into
! 343: CDATA</sitem>
! 344: <sitem>1996-10-02 : TB : remould into skeleton + entities</sitem>
! 345: <sitem>1996-09-30 : CMSMcQ : add a few more sections prior to exchange
! 346: with Tim.</sitem>
! 347: <sitem>1996-09-20 : CMSMcQ : finish transcribing notes.</sitem>
! 348: <sitem>1996-09-19 : CMSMcQ : begin transcribing notes for draft.</sitem>
! 349: <sitem>1996-09-13 : CMSMcQ : made outline from notes of 09-06,
! 350: do some housekeeping</sitem>
! 351: </slist>
! 352: </revisiondesc>
! 353: </header>
! 354: <body>
! 355: <div1 id="sec-intro">
! 356: <head>Introduction</head>
! 357: <p>Extensible Markup Language, abbreviated XML, describes a class of
! 358: data objects called <termref def="dt-xml-doc">XML documents</termref> and
! 359: partially describes the behavior of
! 360: computer programs which process them. XML is an application profile or
! 361: restricted form of SGML, the Standard Generalized Markup
! 362: Language <bibref ref="ISO8879"/>.
! 363: By construction, XML documents
! 364: are conforming SGML documents.
! 365: </p>
! 366: <p>XML documents are made up of storage units called <termref def="dt-entity">entities</termref>, which contain either parsed
! 367: or unparsed data.
! 368: Parsed data is made up of <termref def="dt-character">characters</termref>,
! 369: some
! 370: of which form <termref def="dt-chardata">character data</termref>,
! 371: and some of which form <termref def="dt-markup">markup</termref>.
! 372: Markup encodes a description of the document's storage layout and
! 373: logical structure. XML provides a mechanism to impose constraints on
! 374: the storage layout and logical structure.</p>
! 375: <p><termdef id="dt-xml-proc" term="XML Processor">A software module
! 376: called an <term>XML processor</term> is used to read XML documents
! 377: and provide access to their content and structure.</termdef> <termdef id="dt-app" term="Application">It is assumed that an XML processor is
! 378: doing its work on behalf of another module, called the
! 379: <term>application</term>.</termdef> This specification describes the
! 380: required behavior of an XML processor in terms of how it must read XML
! 381: data and the information it must provide to the application.</p>
! 382:
! 383: <div2 id="sec-origin-goals">
! 384: <head>Origin and Goals</head>
! 385: <p>XML was developed by an XML Working Group (originally known as the
! 386: SGML Editorial Review Board) formed under the auspices of the World
! 387: Wide Web Consortium (W3C) in 1996.
! 388: It was chaired by Jon Bosak of Sun
! 389: Microsystems with the active participation of an XML Special
! 390: Interest Group (previously known as the SGML Working Group) also
! 391: organized by the W3C. The membership of the XML Working Group is given
! 392: in an appendix. Dan Connolly served as the WG's contact with the W3C.
! 393: </p>
! 394: <p>The design goals for XML are:<olist>
! 395: <item><p>XML shall be straightforwardly usable over the
! 396: Internet.</p></item>
! 397: <item><p>XML shall support a wide variety of applications.</p></item>
! 398: <item><p>XML shall be compatible with SGML.</p></item>
! 399: <item><p>It shall be easy to write programs which process XML
! 400: documents.</p></item>
! 401: <item><p>The number of optional features in XML is to be kept to the
! 402: absolute minimum, ideally zero.</p></item>
! 403: <item><p>XML documents should be human-legible and reasonably
! 404: clear.</p></item>
! 405: <item><p>The XML design should be prepared quickly.</p></item>
! 406: <item><p>The design of XML shall be formal and concise.</p></item>
! 407: <item><p>XML documents shall be easy to create.</p></item>
! 408: <item><p>Terseness in XML markup is of minimal importance.</p></item></olist>
! 409: </p>
! 410: <p>This specification,
! 411: together with associated standards
! 412: (Unicode and ISO/IEC 10646 for characters,
! 413: Internet RFC 1766 for language identification tags,
! 414: ISO 639 for language name codes, and
! 415: ISO 3166 for country name codes),
! 416: provides all the information necessary to understand
! 417: XML Version &XML.version;
! 418: and construct computer programs to process it.</p>
! 419: <p>This version of the XML specification
! 420: <!-- is for &doc.audience;.-->
! 421: &doc.distribution;.</p>
! 422:
! 423: </div2>
! 424:
! 425:
! 426:
! 427:
! 428: <div2 id="sec-terminology">
! 429: <head>Terminology</head>
! 430:
! 431: <p>The terminology used to describe XML documents is defined in the body of
! 432: this specification.
! 433: The terms defined in the following list are used in building those
! 434: definitions and in describing the actions of an XML processor:
! 435: <glist>
! 436: <gitem>
! 437: <label>may</label>
! 438: <def><p><termdef id="dt-may" term="May">Conforming documents and XML
! 439: processors are permitted to but need not behave as
! 440: described.</termdef></p></def>
! 441: </gitem>
! 442: <gitem>
! 443: <label>must</label>
! 444: <def><p>Conforming documents and XML processors
! 445: are required to behave as described; otherwise they are in error.
! 446: <!-- do NOT change this! this is what defines a violation of
! 447: a 'must' clause as 'an error'. -MSM -->
! 448: </p></def>
! 449: </gitem>
! 450: <gitem>
! 451: <label>error</label>
! 452: <def><p><termdef id="dt-error" term="Error">A violation of the rules of this
! 453: specification; results are
! 454: undefined. Conforming software may detect and report an error and may
! 455: recover from it.</termdef></p></def>
! 456: </gitem>
! 457: <gitem>
! 458: <label>fatal error</label>
! 459: <def><p><termdef id="dt-fatal" term="Fatal Error">An error
! 460: which a conforming <termref def="dt-xml-proc">XML processor</termref>
! 461: must detect and report to the application.
! 462: After encountering a fatal error, the
! 463: processor may continue
! 464: processing the data to search for further errors and may report such
! 465: errors to the application. In order to support correction of errors,
! 466: the processor may make unprocessed data from the document (with
! 467: intermingled character data and markup) available to the application.
! 468: Once a fatal error is detected, however, the processor must not
! 469: continue normal processing (i.e., it must not
! 470: continue to pass character data and information about the document's
! 471: logical structure to the application in the normal way).
! 472: </termdef></p></def>
! 473: </gitem>
! 474: <gitem>
! 475: <label>at user option</label>
! 476: <def><p>Conforming software may or must (depending on the modal verb in the
! 477: sentence) behave as described; if it does, it must
! 478: provide users a means to enable or disable the behavior
! 479: described.</p></def>
! 480: </gitem>
! 481: <gitem>
! 482: <label>validity constraint</label>
! 483: <def><p>A rule which applies to all
! 484: <termref def="dt-valid">valid</termref> XML documents.
! 485: Violations of validity constraints are errors; they must, at user option,
! 486: be reported by
! 487: <termref def="dt-validating">validating XML processors</termref>.</p></def>
! 488: </gitem>
! 489: <gitem>
! 490: <label>well-formedness constraint</label>
! 491: <def><p>A rule which applies to all <termref def="dt-wellformed">well-formed</termref> XML documents.
! 492: Violations of well-formedness constraints are
! 493: <termref def="dt-fatal">fatal errors</termref>.</p></def>
! 494: </gitem>
! 495:
! 496: <gitem>
! 497: <label>match</label>
! 498: <def><p><termdef id="dt-match" term="match">(Of strings or names:)
! 499: Two strings or names being compared must be identical.
! 500: Characters with multiple possible representations in ISO/IEC 10646 (e.g.
! 501: characters with
! 502: both precomposed and base+diacritic forms) match only if they have the
! 503: same representation in both strings.
! 504: At user option, processors may normalize such characters to
! 505: some canonical form.
! 506: No case folding is performed.
! 507: (Of strings and rules in the grammar:)
! 508: A string matches a grammatical production if it belongs to the
! 509: language generated by that production.
! 510: (Of content and content models:)
! 511: An element matches its declaration when it conforms
! 512: in the fashion described in the constraint
! 513: <specref ref="elementvalid"/>.
! 514: </termdef>
! 515: </p></def>
! 516: </gitem>
! 517: <gitem>
! 518: <label>for compatibility</label>
! 519: <def><p><termdef id="dt-compat" term="For Compatibility">A feature of
! 520: XML included solely to ensure that XML remains compatible with SGML.
! 521: </termdef></p></def>
! 522: </gitem>
! 523: <gitem>
! 524: <label>for interoperability</label>
! 525: <def><p><termdef id="dt-interop" term="For interoperability">A
! 526: non-binding recommendation included to increase the chances that XML
! 527: documents can be processed by the existing installed base of SGML
! 528: processors which predate the
! 529: &WebSGML;.</termdef></p></def>
! 530: </gitem>
! 531: </glist>
! 532: </p>
! 533: </div2>
! 534:
! 535:
! 536: </div1>
! 537: <!-- &Docs; -->
! 538:
! 539: <div1 id="sec-documents">
! 540: <head>Documents</head>
! 541:
! 542: <p><termdef id="dt-xml-doc" term="XML Document">
! 543: A data object is an
! 544: <term>XML document</term> if it is
! 545: <termref def="dt-wellformed">well-formed</termref>, as
! 546: defined in this specification.
! 547: A well-formed XML document may in addition be
! 548: <termref def="dt-valid">valid</termref> if it meets certain further
! 549: constraints.</termdef></p>
! 550:
! 551: <p>Each XML document has both a logical and a physical structure.
! 552: Physically, the document is composed of units called <termref def="dt-entity">entities</termref>. An entity may <termref def="dt-entref">refer</termref> to other entities to cause their
! 553: inclusion in the document. A document begins in a "root" or <termref def="dt-docent">document entity</termref>.
! 554: Logically, the document is composed of declarations, elements,
! 555: comments,
! 556: character references, and
! 557: processing
! 558: instructions, all of which are indicated in the document by explicit
! 559: markup.
! 560: The logical and physical structures must nest properly, as described
! 561: in <specref ref="wf-entities"/>.
! 562: </p>
! 563:
! 564: <div2 id="sec-well-formed">
! 565: <head>Well-Formed XML Documents</head>
! 566:
! 567: <p><termdef id="dt-wellformed" term="Well-Formed">
! 568: A textual object is
! 569: a well-formed XML document if:</termdef>
! 570: <olist>
! 571: <item><p>Taken as a whole, it
! 572: matches the production labeled <nt def="NT-document">document</nt>.</p></item>
! 573: <item><p>It
! 574: meets all the well-formedness constraints given in this specification.</p>
! 575: </item>
! 576: <item><p>Each of the <termref def="dt-parsedent">parsed entities</termref>
! 577: which is referenced directly or indirectly within the document is
! 578: <titleref href="wf-entities">well-formed</titleref>.</p></item>
! 579: </olist></p>
! 580: <p>
! 581: <scrap lang="ebnf" id="document">
! 582: <head>Document</head>
! 583: <prod id="NT-document"><lhs>document</lhs>
! 584: <rhs><nt def="NT-prolog">prolog</nt>
! 585: <nt def="NT-element">element</nt>
! 586: <nt def="NT-Misc">Misc</nt>*</rhs></prod>
! 587: </scrap>
! 588: </p>
! 589: <p>Matching the <nt def="NT-document">document</nt> production
! 590: implies that:
! 591: <olist>
! 592: <item><p>It contains one or more
! 593: <termref def="dt-element">elements</termref>.</p>
! 594: </item>
! 595: <!--* N.B. some readers (notably JC) find the following
! 596: paragraph awkward and redundant. I agree it's logically redundant:
! 597: it *says* it is summarizing the logical implications of
! 598: matching the grammar, and that means by definition it's
! 599: logically redundant. I don't think it's rhetorically
! 600: redundant or unnecessary, though, so I'm keeping it. It
! 601: could however use some recasting when the editors are feeling
! 602: stronger. -MSM *-->
! 603: <item><p><termdef id="dt-root" term="Root Element">There is exactly
! 604: one element, called the <term>root</term>, or document element, no
! 605: part of which appears in the <termref def="dt-content">content</termref> of any other element.</termdef>
! 606: For all other elements, if the start-tag is in the content of another
! 607: element, the end-tag is in the content of the same element. More
! 608: simply stated, the elements, delimited by start- and end-tags, nest
! 609: properly within each other.
! 610: </p></item>
! 611: </olist>
! 612: </p>
! 613: <p><termdef id="dt-parentchild" term="Parent/Child">As a consequence
! 614: of this,
! 615: for each non-root element
! 616: <code>C</code> in the document, there is one other element <code>P</code>
! 617: in the document such that
! 618: <code>C</code> is in the content of <code>P</code>, but is not in
! 619: the content of any other element that is in the content of
! 620: <code>P</code>.
! 621: <code>P</code> is referred to as the
! 622: <term>parent</term> of <code>C</code>, and <code>C</code> as a
! 623: <term>child</term> of <code>P</code>.</termdef></p></div2>
! 624:
! 625: <div2 id="charsets">
! 626: <head>Characters</head>
! 627:
! 628: <p><termdef id="dt-text" term="Text">A parsed entity contains
! 629: <term>text</term>, a sequence of
! 630: <termref def="dt-character">characters</termref>,
! 631: which may represent markup or character data.</termdef>
! 632: <termdef id="dt-character" term="Character">A <term>character</term>
! 633: is an atomic unit of text as specified by
! 634: ISO/IEC 10646 <bibref ref="ISO10646"/>.
! 635: Legal characters are tab, carriage return, line feed, and the legal
! 636: graphic characters of Unicode and ISO/IEC 10646.
! 637: The use of "compatibility characters", as defined in section 6.8
! 638: of <bibref ref="Unicode"/>, is discouraged.
! 639: </termdef>
! 640: <scrap lang="ebnf" id="char32">
! 641: <head>Character Range</head>
! 642: <prodgroup pcw2="4" pcw4="17.5" pcw5="11">
! 643: <prod id="NT-Char"><lhs>Char</lhs>
! 644: <rhs>#x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD]
! 645: | [#x10000-#x10FFFF]</rhs>
! 646: <com>any Unicode character, excluding the
! 647: surrogate blocks, FFFE, and FFFF.</com> </prod>
! 648: </prodgroup>
! 649: </scrap>
! 650: </p>
! 651:
! 652: <p>The mechanism for encoding character code points into bit patterns may
! 653: vary from entity to entity. All XML processors must accept the UTF-8
! 654: and UTF-16 encodings of 10646; the mechanisms for signaling which of
! 655: the two is in use, or for bringing other encodings into play, are
! 656: discussed later, in <specref ref="charencoding"/>.
! 657: </p>
! 658: <!--
! 659: <p>Regardless of the specific encoding used, any character in the ISO/IEC
! 660: 10646 character set may be referred to by the decimal or hexadecimal
! 661: equivalent of its
! 662: UCS-4 code value.
! 663: </p>-->
! 664: </div2>
! 665:
! 666: <div2 id="sec-common-syn">
! 667: <head>Common Syntactic Constructs</head>
! 668:
! 669: <p>This section defines some symbols used widely in the grammar.</p>
! 670: <p><nt def="NT-S">S</nt> (white space) consists of one or more space (#x20)
! 671: characters, carriage returns, line feeds, or tabs.
! 672:
! 673: <scrap lang="ebnf" id="white">
! 674: <head>White Space</head>
! 675: <prodgroup pcw2="4" pcw4="17.5" pcw5="11">
! 676: <prod id="NT-S"><lhs>S</lhs>
! 677: <rhs>(#x20 | #x9 | #xD | #xA)+</rhs>
! 678: </prod>
! 679: </prodgroup>
! 680: </scrap></p>
! 681: <p>Characters are classified for convenience as letters, digits, or other
! 682: characters. Letters consist of an alphabetic or syllabic
! 683: base character possibly
! 684: followed by one or more combining characters, or of an ideographic
! 685: character.
! 686: Full definitions of the specific characters in each class
! 687: are given in <specref ref="CharClasses"/>.</p>
! 688: <p><termdef id="dt-name" term="Name">A <term>Name</term> is a token
! 689: beginning with a letter or one of a few punctuation characters, and continuing
! 690: with letters, digits, hyphens, underscores, colons, or full stops, together
! 691: known as name characters.</termdef>
! 692: Names beginning with the string "<code>xml</code>", or any string
! 693: which would match <code>(('X'|'x') ('M'|'m') ('L'|'l'))</code>, are
! 694: reserved for standardization in this or future versions of this
! 695: specification.
! 696: </p>
! 697: <note>
! 698: <p>The colon character within XML names is reserved for experimentation with
! 699: name spaces.
! 700: Its meaning is expected to be
! 701: standardized at some future point, at which point those documents
! 702: using the colon for experimental purposes may need to be updated.
! 703: (There is no guarantee that any name-space mechanism
! 704: adopted for XML will in fact use the colon as a name-space delimiter.)
! 705: In practice, this means that authors should not use the colon in XML
! 706: names except as part of name-space experiments, but that XML processors
! 707: should accept the colon as a name character.</p>
! 708: </note>
! 709: <p>An
! 710: <nt def="NT-Nmtoken">Nmtoken</nt> (name token) is any mixture of
! 711: name characters.
! 712: <scrap lang="ebnf">
! 713: <head>Names and Tokens</head>
! 714: <prod id="NT-NameChar"><lhs>NameChar</lhs>
! 715: <rhs><nt def="NT-Letter">Letter</nt>
! 716: | <nt def="NT-Digit">Digit</nt>
! 717: | '.' | '-' | '_' | ':'
! 718: | <nt def="NT-CombiningChar">CombiningChar</nt>
! 719: | <nt def="NT-Extender">Extender</nt></rhs>
! 720: </prod>
! 721: <prod id="NT-Name"><lhs>Name</lhs>
! 722: <rhs>(<nt def="NT-Letter">Letter</nt> | '_' | ':')
! 723: (<nt def="NT-NameChar">NameChar</nt>)*</rhs></prod>
! 724: <prod id="NT-Names"><lhs>Names</lhs>
! 725: <rhs><nt def="NT-Name">Name</nt>
! 726: (<nt def="NT-S">S</nt> <nt def="NT-Name">Name</nt>)*</rhs></prod>
! 727: <prod id="NT-Nmtoken"><lhs>Nmtoken</lhs>
! 728: <rhs>(<nt def="NT-NameChar">NameChar</nt>)+</rhs></prod>
! 729: <prod id="NT-Nmtokens"><lhs>Nmtokens</lhs>
! 730: <rhs><nt def="NT-Nmtoken">Nmtoken</nt> (<nt def="NT-S">S</nt> <nt def="NT-Nmtoken">Nmtoken</nt>)*</rhs></prod>
! 731: </scrap>
! 732: </p>
! 733: <p>Literal data is any quoted string not containing
! 734: the quotation mark used as a delimiter for that string.
! 735: Literals are used
! 736: for specifying the content of internal entities
! 737: (<nt def="NT-EntityValue">EntityValue</nt>),
! 738: the values of attributes (<nt def="NT-AttValue">AttValue</nt>),
! 739: and external identifiers
! 740: (<nt def="NT-SystemLiteral">SystemLiteral</nt>).
! 741: Note that a <nt def="NT-SystemLiteral">SystemLiteral</nt>
! 742: can be parsed without scanning for markup.
! 743: <scrap lang="ebnf">
! 744: <head>Literals</head>
! 745: <prod id="NT-EntityValue"><lhs>EntityValue</lhs>
! 746: <rhs>'"'
! 747: ([^%&"]
! 748: | <nt def="NT-PEReference">PEReference</nt>
! 749: | <nt def="NT-Reference">Reference</nt>)*
! 750: '"'
! 751: </rhs>
! 752: <rhs>|
! 753: "'"
! 754: ([^%&']
! 755: | <nt def="NT-PEReference">PEReference</nt>
! 756: | <nt def="NT-Reference">Reference</nt>)*
! 757: "'"</rhs>
! 758: </prod>
! 759: <prod id="NT-AttValue"><lhs>AttValue</lhs>
! 760: <rhs>'"'
! 761: ([^<&"]
! 762: | <nt def="NT-Reference">Reference</nt>)*
! 763: '"'
! 764: </rhs>
! 765: <rhs>|
! 766: "'"
! 767: ([^<&']
! 768: | <nt def="NT-Reference">Reference</nt>)*
! 769: "'"</rhs>
! 770: </prod>
! 771: <prod id="NT-SystemLiteral"><lhs>SystemLiteral</lhs>
! 772: <rhs>('"' [^"]* '"') | ("'" [^']* "'")
! 773: </rhs>
! 774: </prod>
! 775: <prod id="NT-PubidLiteral"><lhs>PubidLiteral</lhs>
! 776: <rhs>'"' <nt def="NT-PubidChar">PubidChar</nt>*
! 777: '"'
! 778: | "'" (<nt def="NT-PubidChar">PubidChar</nt> - "'")* "'"</rhs>
! 779: </prod>
! 780: <prod id="NT-PubidChar"><lhs>PubidChar</lhs>
! 781: <rhs>#x20 | #xD | #xA
! 782: | [a-zA-Z0-9]
! 783: | [-'()+,./:=?;!*#@$_%]</rhs>
! 784: </prod>
! 785: </scrap>
! 786: </p>
! 787:
! 788: </div2>
! 789:
! 790: <div2 id="syntax">
! 791: <head>Character Data and Markup</head>
! 792:
! 793: <p><termref def="dt-text">Text</termref> consists of intermingled
! 794: <termref def="dt-chardata">character
! 795: data</termref> and markup.
! 796: <termdef id="dt-markup" term="Markup"><term>Markup</term> takes the form of
! 797: <termref def="dt-stag">start-tags</termref>,
! 798: <termref def="dt-etag">end-tags</termref>,
! 799: <termref def="dt-empty">empty-element tags</termref>,
! 800: <termref def="dt-entref">entity references</termref>,
! 801: <termref def="dt-charref">character references</termref>,
! 802: <termref def="dt-comment">comments</termref>,
! 803: <termref def="dt-cdsection">CDATA section</termref> delimiters,
! 804: <termref def="dt-doctype">document type declarations</termref>, and
! 805: <termref def="dt-pi">processing instructions</termref>.
! 806: </termdef>
! 807: </p>
! 808: <p><termdef id="dt-chardata" term="Character Data">All text that is not markup
! 809: constitutes the <term>character data</term> of
! 810: the document.</termdef></p>
! 811: <p>The ampersand character (&) and the left angle bracket (<)
! 812: may appear in their literal form <emph>only</emph> when used as markup
! 813: delimiters, or within a <termref def="dt-comment">comment</termref>, a
! 814: <termref def="dt-pi">processing instruction</termref>,
! 815: or a <termref def="dt-cdsection">CDATA section</termref>.
! 816:
! 817: They are also legal within the <termref def="dt-litentval">literal entity
! 818: value</termref> of an internal entity declaration; see
! 819: <specref ref="wf-entities"/>.
! 820: <!-- FINAL EDIT: restore internal entity decl or leave it out. -->
! 821: If they are needed elsewhere,
! 822: they must be <termref def="dt-escape">escaped</termref>
! 823: using either <termref def="dt-charref">numeric character references</termref>
! 824: or the strings
! 825: "<code>&amp;</code>" and "<code>&lt;</code>" respectively.
! 826: The right angle
! 827: bracket (>) may be represented using the string
! 828: "<code>&gt;</code>", and must, <termref def="dt-compat">for
! 829: compatibility</termref>,
! 830: be escaped using
! 831: "<code>&gt;</code>" or a character reference
! 832: when it appears in the string
! 833: "<code>]]></code>"
! 834: in content,
! 835: when that string is not marking the end of
! 836: a <termref def="dt-cdsection">CDATA section</termref>.
! 837: </p>
! 838: <p>
! 839: In the content of elements, character data
! 840: is any string of characters which does
! 841: not contain the start-delimiter of any markup.
! 842: In a CDATA section, character data
! 843: is any string of characters not including the CDATA-section-close
! 844: delimiter, "<code>]]></code>".</p>
! 845: <p>
! 846: To allow attribute values to contain both single and double quotes, the
! 847: apostrophe or single-quote character (') may be represented as
! 848: "<code>&apos;</code>", and the double-quote character (") as
! 849: "<code>&quot;</code>".
! 850: <scrap lang="ebnf">
! 851: <head>Character Data</head>
! 852: <prod id="NT-CharData">
! 853: <lhs>CharData</lhs>
! 854: <rhs>[^<&]* - ([^<&]* ']]>' [^<&]*)</rhs>
! 855: </prod>
! 856: </scrap>
! 857: </p>
! 858: </div2>
! 859:
! 860: <div2 id="sec-comments">
! 861: <head>Comments</head>
! 862:
! 863: <p><termdef id="dt-comment" term="Comment"><term>Comments</term> may
! 864: appear anywhere in a document outside other
! 865: <termref def="dt-markup">markup</termref>; in addition,
! 866: they may appear within the document type declaration
! 867: at places allowed by the grammar.
! 868: They are not part of the document's <termref def="dt-chardata">character
! 869: data</termref>; an XML
! 870: processor may, but need not, make it possible for an application to
! 871: retrieve the text of comments.
! 872: <termref def="dt-compat">For compatibility</termref>, the string
! 873: "<code>--</code>" (double-hyphen) must not occur within
! 874: comments.
! 875: <scrap lang="ebnf">
! 876: <head>Comments</head>
! 877: <prod id="NT-Comment"><lhs>Comment</lhs>
! 878: <rhs>'<!--'
! 879: ((<nt def="NT-Char">Char</nt> - '-')
! 880: | ('-' (<nt def="NT-Char">Char</nt> - '-')))*
! 881: '-->'</rhs>
! 882: </prod>
! 883: </scrap>
! 884: </termdef></p>
! 885: <p>An example of a comment:
! 886: <eg><!&como; declarations for <head> & <body> &comc;></eg>
! 887: </p>
! 888: </div2>
! 889:
! 890: <div2 id="sec-pi">
! 891: <head>Processing Instructions</head>
! 892:
! 893: <p><termdef id="dt-pi" term="Processing instruction"><term>Processing
! 894: instructions</term> (PIs) allow documents to contain instructions
! 895: for applications.
! 896:
! 897: <scrap lang="ebnf">
! 898: <head>Processing Instructions</head>
! 899: <prod id="NT-PI"><lhs>PI</lhs>
! 900: <rhs>'<?' <nt def="NT-PITarget">PITarget</nt>
! 901: (<nt def="NT-S">S</nt>
! 902: (<nt def="NT-Char">Char</nt>* -
! 903: (<nt def="NT-Char">Char</nt>* &pic; <nt def="NT-Char">Char</nt>*)))?
! 904: &pic;</rhs></prod>
! 905: <prod id="NT-PITarget"><lhs>PITarget</lhs>
! 906: <rhs><nt def="NT-Name">Name</nt> -
! 907: (('X' | 'x') ('M' | 'm') ('L' | 'l'))</rhs>
! 908: </prod>
! 909: </scrap></termdef>
! 910: PIs are not part of the document's <termref def="dt-chardata">character
! 911: data</termref>, but must be passed through to the application. The
! 912: PI begins with a target (<nt def="NT-PITarget">PITarget</nt>) used
! 913: to identify the application to which the instruction is directed.
! 914: The target names "<code>XML</code>", "<code>xml</code>", and so on are
! 915: reserved for standardization in this or future versions of this
! 916: specification.
! 917: The
! 918: XML <termref def="dt-notation">Notation</termref> mechanism
! 919: may be used for
! 920: formal declaration of PI targets.
! 921: </p>
! 922: </div2>
! 923:
! 924: <div2 id="sec-cdata-sect">
! 925: <head>CDATA Sections</head>
! 926:
! 927: <p><termdef id="dt-cdsection" term="CDATA Section"><term>CDATA sections</term>
! 928: may occur
! 929: anywhere character data may occur; they are
! 930: used to escape blocks of text containing characters which would
! 931: otherwise be recognized as markup. CDATA sections begin with the
! 932: string "<code><![CDATA[</code>" and end with the string
! 933: "<code>]]></code>":
! 934: <scrap lang="ebnf">
! 935: <head>CDATA Sections</head>
! 936: <prod id="NT-CDSect"><lhs>CDSect</lhs>
! 937: <rhs><nt def="NT-CDStart">CDStart</nt>
! 938: <nt def="NT-CData">CData</nt>
! 939: <nt def="NT-CDEnd">CDEnd</nt></rhs></prod>
! 940: <prod id="NT-CDStart"><lhs>CDStart</lhs>
! 941: <rhs>'<![CDATA['</rhs>
! 942: </prod>
! 943: <prod id="NT-CData"><lhs>CData</lhs>
! 944: <rhs>(<nt def="NT-Char">Char</nt>* -
! 945: (<nt def="NT-Char">Char</nt>* ']]>' <nt def="NT-Char">Char</nt>*))
! 946: </rhs>
! 947: </prod>
! 948: <prod id="NT-CDEnd"><lhs>CDEnd</lhs>
! 949: <rhs>']]>'</rhs>
! 950: </prod>
! 951: </scrap>
! 952:
! 953: Within a CDATA section, only the <nt def="NT-CDEnd">CDEnd</nt> string is
! 954: recognized as markup, so that left angle brackets and ampersands may occur in
! 955: their literal form; they need not (and cannot) be escaped using
! 956: "<code>&lt;</code>" and "<code>&amp;</code>". CDATA sections
! 957: cannot nest.</termdef>
! 958: </p>
! 959:
! 960: <p>An example of a CDATA section, in which "<code><greeting></code>" and
! 961: "<code></greeting></code>"
! 962: are recognized as <termref def="dt-chardata">character data</termref>, not
! 963: <termref def="dt-markup">markup</termref>:
! 964: <eg><![CDATA[<greeting>Hello, world!</greeting>]]></eg>
! 965: </p>
! 966: </div2>
! 967:
! 968: <div2 id="sec-prolog-dtd">
! 969: <head>Prolog and Document Type Declaration</head>
! 970:
! 971: <p><termdef id="dt-xmldecl" term="XML Declaration">XML documents
! 972: may, and should,
! 973: begin with an <term>XML declaration</term> which specifies
! 974: the version of
! 975: XML being used.</termdef>
! 976: For example, the following is a complete XML document, <termref def="dt-wellformed">well-formed</termref> but not
! 977: <termref def="dt-valid">valid</termref>:
! 978: <eg><![CDATA[<?xml version="1.0"?>
! 979: <greeting>Hello, world!</greeting>
! 980: ]]></eg>
! 981: and so is this:
! 982: <eg><![CDATA[<greeting>Hello, world!</greeting>
! 983: ]]></eg>
! 984: </p>
! 985:
! 986: <p>The version number "<code>1.0</code>" should be used to indicate
! 987: conformance to this version of this specification; it is an error
! 988: for a document to use the value "<code>1.0</code>"
! 989: if it does not conform to this version of this specification.
! 990: It is the intent
! 991: of the XML working group to give later versions of this specification
! 992: numbers other than "<code>1.0</code>", but this intent does not
! 993: indicate a
! 994: commitment to produce any future versions of XML, nor if any are produced, to
! 995: use any particular numbering scheme.
! 996: Since future versions are not ruled out, this construct is provided
! 997: as a means to allow the possibility of automatic version recognition, should
! 998: it become necessary.
! 999: Processors may signal an error if they receive documents labeled with
! 1000: versions they do not support.
! 1001: </p>
! 1002: <p>The function of the markup in an XML document is to describe its
! 1003: storage and logical structure and to associate attribute-value pairs
! 1004: with its logical structures. XML provides a mechanism, the <termref def="dt-doctype">document type declaration</termref>, to define
! 1005: constraints on the logical structure and to support the use of
! 1006: predefined storage units.
! 1007:
! 1008: <termdef id="dt-valid" term="Validity">An XML document is
! 1009: <term>valid</term> if it has an associated document type
! 1010: declaration and if the document
! 1011: complies with the constraints expressed in it.</termdef></p>
! 1012: <p>The document type declaration must appear before
! 1013: the first <termref def="dt-element">element</termref> in the document.
! 1014: <scrap lang="ebnf" id="xmldoc">
! 1015: <head>Prolog</head>
! 1016: <prodgroup pcw2="6" pcw4="17.5" pcw5="9">
! 1017: <prod id="NT-prolog"><lhs>prolog</lhs>
! 1018: <rhs><nt def="NT-XMLDecl">XMLDecl</nt>?
! 1019: <nt def="NT-Misc">Misc</nt>*
! 1020: (<nt def="NT-doctypedecl">doctypedecl</nt>
! 1021: <nt def="NT-Misc">Misc</nt>*)?</rhs></prod>
! 1022: <prod id="NT-XMLDecl"><lhs>XMLDecl</lhs>
! 1023: <rhs>&xmlpio;
! 1024: <nt def="NT-VersionInfo">VersionInfo</nt>
! 1025: <nt def="NT-EncodingDecl">EncodingDecl</nt>?
! 1026: <nt def="NT-SDDecl">SDDecl</nt>?
! 1027: <nt def="NT-S">S</nt>?
! 1028: &pic;</rhs>
! 1029: </prod>
! 1030: <prod id="NT-VersionInfo"><lhs>VersionInfo</lhs>
! 1031: <rhs><nt def="NT-S">S</nt> 'version' <nt def="NT-Eq">Eq</nt>
! 1032: (' <nt def="NT-VersionNum">VersionNum</nt> '
! 1033: | " <nt def="NT-VersionNum">VersionNum</nt> ")</rhs>
! 1034: </prod>
! 1035: <prod id="NT-Eq"><lhs>Eq</lhs>
! 1036: <rhs><nt def="NT-S">S</nt>? '=' <nt def="NT-S">S</nt>?</rhs></prod>
! 1037: <prod id="NT-VersionNum">
! 1038: <lhs>VersionNum</lhs>
! 1039: <rhs>([a-zA-Z0-9_.:] | '-')+</rhs>
! 1040: </prod>
! 1041: <prod id="NT-Misc"><lhs>Misc</lhs>
! 1042: <rhs><nt def="NT-Comment">Comment</nt> | <nt def="NT-PI">PI</nt> |
! 1043: <nt def="NT-S">S</nt></rhs></prod>
! 1044: </prodgroup>
! 1045: </scrap></p>
! 1046:
! 1047: <p><termdef id="dt-doctype" term="Document Type Declaration">The XML
! 1048: <term>document type declaration</term>
! 1049: contains or points to
! 1050: <termref def="dt-markupdecl">markup declarations</termref>
! 1051: that provide a grammar for a
! 1052: class of documents.
! 1053: This grammar is known as a document type definition,
! 1054: or <term>DTD</term>.
! 1055: The document type declaration can point to an external subset (a
! 1056: special kind of
! 1057: <termref def="dt-extent">external entity</termref>) containing markup
! 1058: declarations, or can
! 1059: contain the markup declarations directly in an internal subset, or can do
! 1060: both.
! 1061: The DTD for a document consists of both subsets taken
! 1062: together.</termdef>
! 1063: </p>
! 1064: <p><termdef id="dt-markupdecl" term="markup declaration">
! 1065: A <term>markup declaration</term> is
! 1066: an <termref def="dt-eldecl">element type declaration</termref>,
! 1067: an <termref def="dt-attdecl">attribute-list declaration</termref>,
! 1068: an <termref def="dt-entdecl">entity declaration</termref>, or
! 1069: a <termref def="dt-notdecl">notation declaration</termref>.
! 1070: </termdef>
! 1071: These declarations may be contained in whole or in part
! 1072: within <termref def="dt-PE">parameter entities</termref>,
! 1073: as described in the well-formedness and validity constraints below.
! 1074: For fuller information, see
! 1075: <specref ref="sec-physical-struct"/>.</p>
! 1076: <scrap lang="ebnf" id="dtd">
! 1077: <head>Document Type Definition</head>
! 1078: <prodgroup pcw2="6" pcw4="17.5" pcw5="9">
! 1079: <prod id="NT-doctypedecl"><lhs>doctypedecl</lhs>
! 1080: <rhs>'<!DOCTYPE' <nt def="NT-S">S</nt>
! 1081: <nt def="NT-Name">Name</nt> (<nt def="NT-S">S</nt>
! 1082: <nt def="NT-ExternalID">ExternalID</nt>)?
! 1083: <nt def="NT-S">S</nt>? ('['
! 1084: (<nt def="NT-markupdecl">markupdecl</nt>
! 1085: | <nt def="NT-PEReference">PEReference</nt>
! 1086: | <nt def="NT-S">S</nt>)*
! 1087: ']'
! 1088: <nt def="NT-S">S</nt>?)? '>'</rhs>
! 1089: <vc def="vc-roottype"/>
! 1090: </prod>
! 1091: <prod id="NT-markupdecl"><lhs>markupdecl</lhs>
! 1092: <rhs><nt def="NT-elementdecl">elementdecl</nt>
! 1093: | <nt def="NT-AttlistDecl">AttlistDecl</nt>
! 1094: | <nt def="NT-EntityDecl">EntityDecl</nt>
! 1095: | <nt def="NT-NotationDecl">NotationDecl</nt>
! 1096: | <nt def="NT-PI">PI</nt>
! 1097: | <nt def="NT-Comment">Comment</nt>
! 1098: </rhs>
! 1099: <vc def="vc-PEinMarkupDecl"/>
! 1100: <wfc def="wfc-PEinInternalSubset"/>
! 1101: </prod>
! 1102:
! 1103: </prodgroup>
! 1104: </scrap>
! 1105:
! 1106: <p>The markup declarations may be made up in whole or in part of
! 1107: the <termref def="dt-repltext">replacement text</termref> of
! 1108: <termref def="dt-PE">parameter entities</termref>.
! 1109: The productions later in this specification for
! 1110: individual nonterminals (<nt def="NT-elementdecl">elementdecl</nt>,
! 1111: <nt def="NT-AttlistDecl">AttlistDecl</nt>, and so on) describe
! 1112: the declarations <emph>after</emph> all the parameter entities have been
! 1113: <termref def="dt-include">included</termref>.</p>
! 1114:
! 1115: <vcnote id="vc-roottype">
! 1116: <head>Root Element Type</head>
! 1117: <p>
! 1118: The <nt def="NT-Name">Name</nt> in the document type declaration must
! 1119: match the element type of the <termref def="dt-root">root element</termref>.
! 1120: </p>
! 1121: </vcnote>
! 1122:
! 1123: <vcnote id="vc-PEinMarkupDecl">
! 1124: <head>Proper Declaration/PE Nesting</head>
! 1125: <p>Parameter-entity
! 1126: <termref def="dt-repltext">replacement text</termref> must be properly nested
! 1127: with markup declarations.
! 1128: That is to say, if either the first character
! 1129: or the last character of a markup
! 1130: declaration (<nt def="NT-markupdecl">markupdecl</nt> above)
! 1131: is contained in the replacement text for a
! 1132: <termref def="dt-PERef">parameter-entity reference</termref>,
! 1133: both must be contained in the same replacement text.</p>
! 1134: </vcnote>
! 1135: <wfcnote id="wfc-PEinInternalSubset">
! 1136: <head>PEs in Internal Subset</head>
! 1137: <p>In the internal DTD subset,
! 1138: <termref def="dt-PERef">parameter-entity references</termref>
! 1139: can occur only where markup declarations can occur, not
! 1140: within markup declarations. (This does not apply to
! 1141: references that occur in
! 1142: external parameter entities or to the external subset.)
! 1143: </p>
! 1144: </wfcnote>
! 1145: <p>
! 1146: Like the internal subset, the external subset and
! 1147: any external parameter entities referred to in the DTD
! 1148: must consist of a series of complete markup declarations of the types
! 1149: allowed by the non-terminal symbol
! 1150: <nt def="NT-markupdecl">markupdecl</nt>, interspersed with white space
! 1151: or <termref def="dt-PERef">parameter-entity references</termref>.
! 1152: However, portions of the contents
! 1153: of the
! 1154: external subset or of external parameter entities may conditionally be ignored
! 1155: by using
! 1156: the <termref def="dt-cond-section">conditional section</termref>
! 1157: construct; this is not allowed in the internal subset.
! 1158:
! 1159: <scrap id="ext-Subset">
! 1160: <head>External Subset</head>
! 1161: <prodgroup pcw2="6" pcw4="17.5" pcw5="9">
! 1162: <prod id="NT-extSubset"><lhs>extSubset</lhs>
! 1163: <rhs><nt def="NT-TextDecl">TextDecl</nt>?
! 1164: <nt def="NT-extSubsetDecl">extSubsetDecl</nt></rhs></prod>
! 1165: <prod id="NT-extSubsetDecl"><lhs>extSubsetDecl</lhs>
! 1166: <rhs>(
! 1167: <nt def="NT-markupdecl">markupdecl</nt>
! 1168: | <nt def="NT-conditionalSect">conditionalSect</nt>
! 1169: | <nt def="NT-PEReference">PEReference</nt>
! 1170: | <nt def="NT-S">S</nt>
! 1171: )*</rhs>
! 1172: </prod>
! 1173: </prodgroup>
! 1174: </scrap></p>
! 1175: <p>The external subset and external parameter entities also differ
! 1176: from the internal subset in that in them,
! 1177: <termref def="dt-PERef">parameter-entity references</termref>
! 1178: are permitted <emph>within</emph> markup declarations,
! 1179: not only <emph>between</emph> markup declarations.</p>
! 1180: <p>An example of an XML document with a document type declaration:
! 1181: <eg><![CDATA[<?xml version="1.0"?>
! 1182: <!DOCTYPE greeting SYSTEM "hello.dtd">
! 1183: <greeting>Hello, world!</greeting>
! 1184: ]]></eg>
! 1185: The <termref def="dt-sysid">system identifier</termref>
! 1186: "<code>hello.dtd</code>" gives the URI of a DTD for the document.</p>
! 1187: <p>The declarations can also be given locally, as in this
! 1188: example:
! 1189: <eg><![CDATA[<?xml version="1.0" encoding="UTF-8" ?>
! 1190: <!DOCTYPE greeting [
! 1191: <!ELEMENT greeting (#PCDATA)>
! 1192: ]>
! 1193: <greeting>Hello, world!</greeting>
! 1194: ]]></eg>
! 1195: If both the external and internal subsets are used, the
! 1196: internal subset is considered to occur before the external subset.
! 1197: <!-- 'is considered to'? boo. whazzat mean? -->
! 1198: This has the effect that entity and attribute-list declarations in the
! 1199: internal subset take precedence over those in the external subset.
! 1200: </p>
! 1201: </div2>
! 1202:
! 1203: <div2 id="sec-rmd">
! 1204: <head>Standalone Document Declaration</head>
! 1205: <p>Markup declarations can affect the content of the document,
! 1206: as passed from an <termref def="dt-xml-proc">XML processor</termref>
! 1207: to an application; examples are attribute defaults and entity
! 1208: declarations.
! 1209: The standalone document declaration,
! 1210: which may appear as a component of the XML declaration, signals
! 1211: whether or not there are such declarations which appear external to
! 1212: the <termref def="dt-docent">document entity</termref>.
! 1213: <scrap lang="ebnf" id="fulldtd">
! 1214: <head>Standalone Document Declaration</head>
! 1215: <prodgroup pcw2="4" pcw4="19.5" pcw5="9">
! 1216: <prod id="NT-SDDecl"><lhs>SDDecl</lhs>
! 1217: <rhs>
! 1218: <nt def="NT-S">S</nt>
! 1219: 'standalone' <nt def="NT-Eq">Eq</nt>
! 1220: (("'" ('yes' | 'no') "'") | ('"' ('yes' | 'no') '"'))
! 1221: </rhs>
! 1222: <vc def="vc-check-rmd"/></prod>
! 1223: </prodgroup>
! 1224: </scrap></p>
! 1225: <p>
! 1226: In a standalone document declaration, the value "<code>yes</code>" indicates
! 1227: that there
! 1228: are no markup declarations external to the <termref def="dt-docent">document
! 1229: entity</termref> (either in the DTD external subset, or in an
! 1230: external parameter entity referenced from the internal subset)
! 1231: which affect the information passed from the XML processor to
! 1232: the application.
! 1233: The value "<code>no</code>" indicates that there are or may be such
! 1234: external markup declarations.
! 1235: Note that the standalone document declaration only
! 1236: denotes the presence of external <emph>declarations</emph>; the presence, in a
! 1237: document, of
! 1238: references to external <emph>entities</emph>, when those entities are
! 1239: internally declared,
! 1240: does not change its standalone status.</p>
! 1241: <p>If there are no external markup declarations, the standalone document
! 1242: declaration has no meaning.
! 1243: If there are external markup declarations but there is no standalone
! 1244: document declaration, the value "<code>no</code>" is assumed.</p>
! 1245: <p>Any XML document for which <code>standalone="no"</code> holds can
! 1246: be converted algorithmically to a standalone document,
! 1247: which may be desirable for some network delivery applications.</p>
! 1248: <vcnote id="vc-check-rmd">
! 1249: <head>Standalone Document Declaration</head>
! 1250: <p>The standalone document declaration must have
! 1251: the value "<code>no</code>" if any external markup declarations
! 1252: contain declarations of:</p><ulist>
! 1253: <item><p>attributes with <termref def="dt-default">default</termref> values, if
! 1254: elements to which
! 1255: these attributes apply appear in the document without
! 1256: specifications of values for these attributes, or</p></item>
! 1257: <item><p>entities (other than &magicents;),
! 1258: if <termref def="dt-entref">references</termref> to those
! 1259: entities appear in the document, or</p>
! 1260: </item>
! 1261: <item><p>attributes with values subject to
! 1262: <titleref href="AVNormalize">normalization</titleref>, where the
! 1263: attribute appears in the document with a value which will
! 1264: change as a result of normalization, or</p>
! 1265: </item>
! 1266: <item>
! 1267: <p>element types with <termref def="dt-elemcontent">element content</termref>,
! 1268: if white space occurs
! 1269: directly within any instance of those types.
! 1270: </p></item>
! 1271: </ulist>
! 1272:
! 1273: </vcnote>
! 1274: <p>An example XML declaration with a standalone document declaration:<eg><?xml version="&XML.version;" standalone='yes'?></eg></p>
! 1275: </div2>
! 1276: <div2 id="sec-white-space">
! 1277: <head>White Space Handling</head>
! 1278:
! 1279: <p>In editing XML documents, it is often convenient to use "white space"
! 1280: (spaces, tabs, and blank lines, denoted by the nonterminal
! 1281: <nt def="NT-S">S</nt> in this specification) to
! 1282: set apart the markup for greater readability. Such white space is typically
! 1283: not intended for inclusion in the delivered version of the document.
! 1284: On the other hand, "significant" white space that should be preserved in the
! 1285: delivered version is common, for example in poetry and
! 1286: source code.</p>
! 1287: <p>An <termref def="dt-xml-proc">XML processor</termref>
! 1288: must always pass all characters in a document that are not
! 1289: markup through to the application. A <termref def="dt-validating">
! 1290: validating XML processor</termref> must also inform the application
! 1291: which of these characters constitute white space appearing
! 1292: in <termref def="dt-elemcontent">element content</termref>.
! 1293: </p>
! 1294: <p>A special <termref def="dt-attr">attribute</termref>
! 1295: named <kw>xml:space</kw> may be attached to an element
! 1296: to signal an intention that in that element,
! 1297: white space should be preserved by applications.
! 1298: In valid documents, this attribute, like any other, must be
! 1299: <termref def="dt-attdecl">declared</termref> if it is used.
! 1300: When declared, it must be given as an
! 1301: <termref def="dt-enumerated">enumerated type</termref> whose only
! 1302: possible values are "<code>default</code>" and "<code>preserve</code>".
! 1303: For example:<eg><![CDATA[ <!ATTLIST poem xml:space (default|preserve) 'preserve'>]]></eg></p>
! 1304: <p>The value "<code>default</code>" signals that applications'
! 1305: default white-space processing modes are acceptable for this element; the
! 1306: value "<code>preserve</code>" indicates the intent that applications preserve
! 1307: all the white space.
! 1308: This declared intent is considered to apply to all elements within the content
! 1309: of the element where it is specified, unless overriden with another instance
! 1310: of the <kw>xml:space</kw> attribute.
! 1311: </p>
! 1312: <p>The <termref def="dt-root">root element</termref> of any document
! 1313: is considered to have signaled no intentions as regards application space
! 1314: handling, unless it provides a value for
! 1315: this attribute or the attribute is declared with a default value.
! 1316: </p>
! 1317:
! 1318: </div2>
! 1319: <div2 id="sec-line-ends">
! 1320: <head>End-of-Line Handling</head>
! 1321: <p>XML <termref def="dt-parsedent">parsed entities</termref> are often stored in
! 1322: computer files which, for editing convenience, are organized into lines.
! 1323: These lines are typically separated by some combination of the characters
! 1324: carriage-return (#xD) and line-feed (#xA).</p>
! 1325: <p>To simplify the tasks of <termref def="dt-app">applications</termref>,
! 1326: wherever an external parsed entity or the literal entity value
! 1327: of an internal parsed entity contains either the literal
! 1328: two-character sequence "#xD#xA" or a standalone literal
! 1329: #xD, an <termref def="dt-xml-proc">XML processor</termref> must
! 1330: pass to the application the single character #xA.
! 1331: (This behavior can
! 1332: conveniently be produced by normalizing all
! 1333: line breaks to #xA on input, before parsing.)
! 1334: </p>
! 1335: </div2>
! 1336: <div2 id="sec-lang-tag">
! 1337: <head>Language Identification</head>
! 1338: <p>In document processing, it is often useful to
! 1339: identify the natural or formal language
! 1340: in which the content is
! 1341: written.
! 1342: A special <termref def="dt-attr">attribute</termref> named
! 1343: <kw>xml:lang</kw> may be inserted in
! 1344: documents to specify the
! 1345: language used in the contents and attribute values
! 1346: of any element in an XML document.
! 1347: In valid documents, this attribute, like any other, must be
! 1348: <termref def="dt-attdecl">declared</termref> if it is used.
! 1349: The values of the attribute are language identifiers as defined
! 1350: by <bibref ref="RFC1766"/>, "Tags for the Identification of Languages":
! 1351: <scrap lang="ebnf">
! 1352: <head>Language Identification</head>
! 1353: <prod id="NT-LanguageID"><lhs>LanguageID</lhs>
! 1354: <rhs><nt def="NT-Langcode">Langcode</nt>
! 1355: ('-' <nt def="NT-Subcode">Subcode</nt>)*</rhs></prod>
! 1356: <prod id="NT-Langcode"><lhs>Langcode</lhs>
! 1357: <rhs><nt def="NT-ISO639Code">ISO639Code</nt> |
! 1358: <nt def="NT-IanaCode">IanaCode</nt> |
! 1359: <nt def="NT-UserCode">UserCode</nt></rhs>
! 1360: </prod>
! 1361: <prod id="NT-ISO639Code"><lhs>ISO639Code</lhs>
! 1362: <rhs>([a-z] | [A-Z]) ([a-z] | [A-Z])</rhs></prod>
! 1363: <prod id="NT-IanaCode"><lhs>IanaCode</lhs>
! 1364: <rhs>('i' | 'I') '-' ([a-z] | [A-Z])+</rhs></prod>
! 1365: <prod id="NT-UserCode"><lhs>UserCode</lhs>
! 1366: <rhs>('x' | 'X') '-' ([a-z] | [A-Z])+</rhs></prod>
! 1367: <prod id="NT-Subcode"><lhs>Subcode</lhs>
! 1368: <rhs>([a-z] | [A-Z])+</rhs></prod>
! 1369: </scrap>
! 1370: The <nt def="NT-Langcode">Langcode</nt> may be any of the following:
! 1371: <ulist>
! 1372: <item><p>a two-letter language code as defined by
! 1373: <bibref ref="ISO639"/>, "Codes
! 1374: for the representation of names of languages"</p></item>
! 1375: <item><p>a language identifier registered with the Internet
! 1376: Assigned Numbers Authority <bibref ref="IANA"/>; these begin with the
! 1377: prefix "<code>i-</code>" (or "<code>I-</code>")</p></item>
! 1378: <item><p>a language identifier assigned by the user, or agreed on
! 1379: between parties in private use; these must begin with the
! 1380: prefix "<code>x-</code>" or "<code>X-</code>" in order to ensure that they do not conflict
! 1381: with names later standardized or registered with IANA</p></item>
! 1382: </ulist></p>
! 1383: <p>There may be any number of <nt def="NT-Subcode">Subcode</nt> segments; if
! 1384: the first
! 1385: subcode segment exists and the Subcode consists of two
! 1386: letters, then it must be a country code from
! 1387: <bibref ref="ISO3166"/>, "Codes
! 1388: for the representation of names of countries."
! 1389: If the first
! 1390: subcode consists of more than two letters, it must be
! 1391: a subcode for the language in question registered with IANA,
! 1392: unless the <nt def="NT-Langcode">Langcode</nt> begins with the prefix
! 1393: "<code>x-</code>" or
! 1394: "<code>X-</code>". </p>
! 1395: <p>It is customary to give the language code in lower case, and
! 1396: the country code (if any) in upper case.
! 1397: Note that these values, unlike other names in XML documents,
! 1398: are case insensitive.</p>
! 1399: <p>For example:
! 1400: <eg><![CDATA[<p xml:lang="en">The quick brown fox jumps over the lazy dog.</p>
! 1401: <p xml:lang="en-GB">What colour is it?</p>
! 1402: <p xml:lang="en-US">What color is it?</p>
! 1403: <sp who="Faust" desc='leise' xml:lang="de">
! 1404: <l>Habe nun, ach! Philosophie,</l>
! 1405: <l>Juristerei, und Medizin</l>
! 1406: <l>und leider auch Theologie</l>
! 1407: <l>durchaus studiert mit heißem Bemüh'n.</l>
! 1408: </sp>]]></eg></p>
! 1409: <!--<p>The xml:lang value is considered to apply both to the contents of an
! 1410: element and
! 1411: (unless otherwise via attribute default values) to the
! 1412: values of all of its attributes with free-text (CDATA) values. -->
! 1413: <p>The intent declared with <kw>xml:lang</kw> is considered to apply to
! 1414: all attributes and content of the element where it is specified,
! 1415: unless overridden with an instance of <kw>xml:lang</kw>
! 1416: on another element within that content.</p>
! 1417: <!--
! 1418: If no
! 1419: value is specified for xml:lang on an element, and no default value is
! 1420: defined for it in the DTD, then the xml:lang attribute of any element
! 1421: takes the same value it has in the parent element, if any. The two
! 1422: technical terms in the following example both have the same effective
! 1423: value for xml:lang:
! 1424:
! 1425: <p xml:lang="en">Here the keywords are
! 1426: <term xml:lang="en">shift</term> and
! 1427: <term>reduce</term>. ...</p>
! 1428:
! 1429: The application, not the XML processor, is responsible for this '
! 1430: inheritance' of attribute values.
! 1431: -->
! 1432: <p>A simple declaration for <kw>xml:lang</kw> might take
! 1433: the form
! 1434: <eg>xml:lang NMTOKEN #IMPLIED</eg>
! 1435: but specific default values may also be given, if appropriate. In a
! 1436: collection of French poems for English students, with glosses and
! 1437: notes in English, the xml:lang attribute might be declared this way:
! 1438: <eg><![CDATA[ <!ATTLIST poem xml:lang NMTOKEN 'fr'>
! 1439: <!ATTLIST gloss xml:lang NMTOKEN 'en'>
! 1440: <!ATTLIST note xml:lang NMTOKEN 'en'>]]></eg>
! 1441: </p>
! 1442:
! 1443: </div2>
! 1444: </div1>
! 1445: <!-- &Elements; -->
! 1446:
! 1447: <div1 id="sec-logical-struct">
! 1448: <head>Logical Structures</head>
! 1449:
! 1450: <p><termdef id="dt-element" term="Element">Each <termref def="dt-xml-doc">XML document</termref> contains one or more
! 1451: <term>elements</term>, the boundaries of which are
! 1452: either delimited by <termref def="dt-stag">start-tags</termref>
! 1453: and <termref def="dt-etag">end-tags</termref>, or, for <termref def="dt-empty">empty</termref> elements, by an <termref def="dt-eetag">empty-element tag</termref>. Each element has a type,
! 1454: identified by name, sometimes called its "generic
! 1455: identifier" (GI), and may have a set of
! 1456: attribute specifications.</termdef> Each attribute specification
! 1457: has a <termref def="dt-attrname">name</termref> and a <termref def="dt-attrval">value</termref>.
! 1458: </p>
! 1459: <scrap lang="ebnf"><head>Element</head>
! 1460: <prod id="NT-element"><lhs>element</lhs>
! 1461: <rhs><nt def="NT-EmptyElemTag">EmptyElemTag</nt></rhs>
! 1462: <rhs>| <nt def="NT-STag">STag</nt> <nt def="NT-content">content</nt>
! 1463: <nt def="NT-ETag">ETag</nt></rhs>
! 1464: <wfc def="GIMatch"/>
! 1465: <vc def="elementvalid"/>
! 1466: </prod>
! 1467: </scrap>
! 1468: <p>This specification does not constrain the semantics, use, or (beyond
! 1469: syntax) names of the element types and attributes, except that names
! 1470: beginning with a match to <code>(('X'|'x')('M'|'m')('L'|'l'))</code>
! 1471: are reserved for standardization in this or future versions of this
! 1472: specification.
! 1473: </p>
! 1474: <wfcnote id="GIMatch">
! 1475: <head>Element Type Match</head>
! 1476: <p>
! 1477: The <nt def="NT-Name">Name</nt> in an element's end-tag must match
! 1478: the element type in
! 1479: the start-tag.
! 1480: </p>
! 1481: </wfcnote>
! 1482: <vcnote id="elementvalid">
! 1483: <head>Element Valid</head>
! 1484: <p>An element is
! 1485: valid if
! 1486: there is a declaration matching
! 1487: <nt def="NT-elementdecl">elementdecl</nt> where the
! 1488: <nt def="NT-Name">Name</nt> matches the element type, and
! 1489: one of the following holds:</p>
! 1490: <olist>
! 1491: <item><p>The declaration matches <kw>EMPTY</kw> and the element has no
! 1492: <termref def="dt-content">content</termref>.</p></item>
! 1493: <item><p>The declaration matches <nt def="NT-children">children</nt> and
! 1494: the sequence of
! 1495: <termref def="dt-parentchild">child elements</termref>
! 1496: belongs to the language generated by the regular expression in
! 1497: the content model, with optional white space (characters
! 1498: matching the nonterminal <nt def="NT-S">S</nt>) between each pair
! 1499: of child elements.</p></item>
! 1500: <item><p>The declaration matches <nt def="NT-Mixed">Mixed</nt> and
! 1501: the content consists of <termref def="dt-chardata">character
! 1502: data</termref> and <termref def="dt-parentchild">child elements</termref>
! 1503: whose types match names in the content model.</p></item>
! 1504: <item><p>The declaration matches <kw>ANY</kw>, and the types
! 1505: of any <termref def="dt-parentchild">child elements</termref> have
! 1506: been declared.</p></item>
! 1507: </olist>
! 1508: </vcnote>
! 1509:
! 1510: <div2 id="sec-starttags">
! 1511: <head>Start-Tags, End-Tags, and Empty-Element Tags</head>
! 1512:
! 1513: <p><termdef id="dt-stag" term="Start-Tag">The beginning of every
! 1514: non-empty XML element is marked by a <term>start-tag</term>.
! 1515: <scrap lang="ebnf">
! 1516: <head>Start-tag</head>
! 1517: <prodgroup pcw2="6" pcw4="15" pcw5="11.5">
! 1518: <prod id="NT-STag"><lhs>STag</lhs>
! 1519: <rhs>'<' <nt def="NT-Name">Name</nt>
! 1520: (<nt def="NT-S">S</nt> <nt def="NT-Attribute">Attribute</nt>)*
! 1521: <nt def="NT-S">S</nt>? '>'</rhs>
! 1522: <wfc def="uniqattspec"/>
! 1523: </prod>
! 1524: <prod id="NT-Attribute"><lhs>Attribute</lhs>
! 1525: <rhs><nt def="NT-Name">Name</nt> <nt def="NT-Eq">Eq</nt>
! 1526: <nt def="NT-AttValue">AttValue</nt></rhs>
! 1527: <vc def="ValueType"/>
! 1528: <wfc def="NoExternalRefs"/>
! 1529: <wfc def="CleanAttrVals"/></prod>
! 1530: </prodgroup>
! 1531: </scrap>
! 1532: The <nt def="NT-Name">Name</nt> in
! 1533: the start- and end-tags gives the
! 1534: element's <term>type</term>.</termdef>
! 1535: <termdef id="dt-attr" term="Attribute">
! 1536: The <nt def="NT-Name">Name</nt>-<nt def="NT-AttValue">AttValue</nt> pairs are
! 1537: referred to as
! 1538: the <term>attribute specifications</term> of the element</termdef>,
! 1539: <termdef id="dt-attrname" term="Attribute Name">with the
! 1540: <nt def="NT-Name">Name</nt> in each pair
! 1541: referred to as the <term>attribute name</term></termdef> and
! 1542: <termdef id="dt-attrval" term="Attribute Value">the content of the
! 1543: <nt def="NT-AttValue">AttValue</nt> (the text between the
! 1544: <code>'</code> or <code>"</code> delimiters)
! 1545: as the <term>attribute value</term>.</termdef>
! 1546: </p>
! 1547: <wfcnote id="uniqattspec">
! 1548: <head>Unique Att Spec</head>
! 1549: <p>
! 1550: No attribute name may appear more than once in the same start-tag
! 1551: or empty-element tag.
! 1552: </p>
! 1553: </wfcnote>
! 1554: <vcnote id="ValueType">
! 1555: <head>Attribute Value Type</head>
! 1556: <p>
! 1557: The attribute must have been declared; the value must be of the type
! 1558: declared for it.
! 1559: (For attribute types, see <specref ref="attdecls"/>.)
! 1560: </p>
! 1561: </vcnote>
! 1562: <wfcnote id="NoExternalRefs">
! 1563: <head>No External Entity References</head>
! 1564: <p>
! 1565: Attribute values cannot contain direct or indirect entity references
! 1566: to external entities.
! 1567: </p>
! 1568: </wfcnote>
! 1569: <wfcnote id="CleanAttrVals">
! 1570: <head>No <code><</code> in Attribute Values</head>
! 1571: <p>The <termref def="dt-repltext">replacement text</termref> of any entity
! 1572: referred to directly or indirectly in an attribute
! 1573: value (other than "<code>&lt;</code>") must not contain
! 1574: a <code><</code>.
! 1575: </p></wfcnote>
! 1576: <p>An example of a start-tag:
! 1577: <eg><termdef id="dt-dog" term="dog"></eg></p>
! 1578: <p><termdef id="dt-etag" term="End Tag">The end of every element
! 1579: that begins with a start-tag must
! 1580: be marked by an <term>end-tag</term>
! 1581: containing a name that echoes the element's type as given in the
! 1582: start-tag:
! 1583: <scrap lang="ebnf">
! 1584: <head>End-tag</head>
! 1585: <prodgroup pcw2="6" pcw4="15" pcw5="11.5">
! 1586: <prod id="NT-ETag"><lhs>ETag</lhs>
! 1587: <rhs>'</' <nt def="NT-Name">Name</nt>
! 1588: <nt def="NT-S">S</nt>? '>'</rhs></prod>
! 1589: </prodgroup>
! 1590: </scrap>
! 1591: </termdef></p>
! 1592: <p>An example of an end-tag:<eg></termdef></eg></p>
! 1593: <p><termdef id="dt-content" term="Content">The
! 1594: <termref def="dt-text">text</termref> between the start-tag and
! 1595: end-tag is called the element's
! 1596: <term>content</term>:
! 1597: <scrap lang="ebnf">
! 1598: <head>Content of Elements</head>
! 1599: <prodgroup pcw2="6" pcw4="15" pcw5="11.5">
! 1600: <prod id="NT-content"><lhs>content</lhs>
! 1601: <rhs>(<nt def="NT-element">element</nt> | <nt def="NT-CharData">CharData</nt>
! 1602: | <nt def="NT-Reference">Reference</nt> | <nt def="NT-CDSect">CDSect</nt>
! 1603: | <nt def="NT-PI">PI</nt> | <nt def="NT-Comment">Comment</nt>)*</rhs>
! 1604: </prod>
! 1605: </prodgroup>
! 1606: </scrap>
! 1607: </termdef></p>
! 1608: <p><termdef id="dt-empty" term="Empty">If an element is <term>empty</term>,
! 1609: it must be represented either by a start-tag immediately followed
! 1610: by an end-tag or by an empty-element tag.</termdef>
! 1611: <termdef id="dt-eetag" term="empty-element tag">An
! 1612: <term>empty-element tag</term> takes a special form:
! 1613: <scrap lang="ebnf">
! 1614: <head>Tags for Empty Elements</head>
! 1615: <prodgroup pcw2="6" pcw4="15" pcw5="11.5">
! 1616: <prod id="NT-EmptyElemTag"><lhs>EmptyElemTag</lhs>
! 1617: <rhs>'<' <nt def="NT-Name">Name</nt> (<nt def="NT-S">S</nt>
! 1618: <nt def="NT-Attribute">Attribute</nt>)* <nt def="NT-S">S</nt>?
! 1619: '/>'</rhs>
! 1620: <wfc def="uniqattspec"/>
! 1621: </prod>
! 1622: </prodgroup>
! 1623: </scrap>
! 1624: </termdef></p>
! 1625: <p>Empty-element tags may be used for any element which has no
! 1626: content, whether or not it is declared using the keyword
! 1627: <kw>EMPTY</kw>.
! 1628: <termref def="dt-interop">For interoperability</termref>, the empty-element
! 1629: tag must be used, and can only be used, for elements which are
! 1630: <termref def="dt-eldecl">declared</termref> <kw>EMPTY</kw>.</p>
! 1631: <p>Examples of empty elements:
! 1632: <eg><IMG align="left"
! 1633: src="http://www.w3.org/Icons/WWW/w3c_home" />
! 1634: <br></br>
! 1635: <br/></eg></p>
! 1636: </div2>
! 1637:
! 1638: <div2 id="elemdecls">
! 1639: <head>Element Type Declarations</head>
! 1640:
! 1641: <p>The <termref def="dt-element">element</termref> structure of an
! 1642: <termref def="dt-xml-doc">XML document</termref> may, for
! 1643: <termref def="dt-valid">validation</termref> purposes,
! 1644: be constrained
! 1645: using element type and attribute-list declarations.
! 1646: An element type declaration constrains the element's
! 1647: <termref def="dt-content">content</termref>.
! 1648: </p>
! 1649:
! 1650: <p>Element type declarations often constrain which element types can
! 1651: appear as <termref def="dt-parentchild">children</termref> of the element.
! 1652: At user option, an XML processor may issue a warning
! 1653: when a declaration mentions an element type for which no declaration
! 1654: is provided, but this is not an error.</p>
! 1655: <p><termdef id="dt-eldecl" term="Element Type declaration">An <term>element
! 1656: type declaration</term> takes the form:
! 1657: <scrap lang="ebnf">
! 1658: <head>Element Type Declaration</head>
! 1659: <prodgroup pcw2="5.5" pcw4="18" pcw5="9">
! 1660: <prod id="NT-elementdecl"><lhs>elementdecl</lhs>
! 1661: <rhs>'<!ELEMENT' <nt def="NT-S">S</nt>
! 1662: <nt def="NT-Name">Name</nt>
! 1663: <nt def="NT-S">S</nt>
! 1664: <nt def="NT-contentspec">contentspec</nt>
! 1665: <nt def="NT-S">S</nt>? '>'</rhs>
! 1666: <vc def="EDUnique"/></prod>
! 1667: <prod id="NT-contentspec"><lhs>contentspec</lhs>
! 1668: <rhs>'EMPTY'
! 1669: | 'ANY'
! 1670: | <nt def="NT-Mixed">Mixed</nt>
! 1671: | <nt def="NT-children">children</nt>
! 1672: </rhs>
! 1673: </prod>
! 1674: </prodgroup>
! 1675: </scrap>
! 1676: where the <nt def="NT-Name">Name</nt> gives the element type
! 1677: being declared.</termdef>
! 1678: </p>
! 1679:
! 1680: <vcnote id="EDUnique">
! 1681: <head>Unique Element Type Declaration</head>
! 1682: <p>
! 1683: No element type may be declared more than once.
! 1684: </p>
! 1685: </vcnote>
! 1686:
! 1687: <p>Examples of element type declarations:
! 1688: <eg><!ELEMENT br EMPTY>
! 1689: <!ELEMENT p (#PCDATA|emph)* >
! 1690: <!ELEMENT %name.para; %content.para; >
! 1691: <!ELEMENT container ANY></eg></p>
! 1692:
! 1693: <div3 id="sec-element-content">
! 1694: <head>Element Content</head>
! 1695:
! 1696: <p><termdef id="dt-elemcontent" term="Element content">An element <termref def="dt-stag">type</termref> has
! 1697: <term>element content</term> when elements of that
! 1698: type must contain only <termref def="dt-parentchild">child</termref>
! 1699: elements (no character data), optionally separated by
! 1700: white space (characters matching the nonterminal
! 1701: <nt def="NT-S">S</nt>).
! 1702: </termdef>
! 1703: In this case, the
! 1704: constraint includes a content model, a simple grammar governing
! 1705: the allowed types of the child
! 1706: elements and the order in which they are allowed to appear.
! 1707: The grammar is built on
! 1708: content particles (<nt def="NT-cp">cp</nt>s), which consist of names,
! 1709: choice lists of content particles, or
! 1710: sequence lists of content particles:
! 1711: <scrap lang="ebnf">
! 1712: <head>Element-content Models</head>
! 1713: <prodgroup pcw2="5.5" pcw4="16" pcw5="11">
! 1714: <prod id="NT-children"><lhs>children</lhs>
! 1715: <rhs>(<nt def="NT-choice">choice</nt>
! 1716: | <nt def="NT-seq">seq</nt>)
! 1717: ('?' | '*' | '+')?</rhs></prod>
! 1718: <prod id="NT-cp"><lhs>cp</lhs>
! 1719: <rhs>(<nt def="NT-Name">Name</nt>
! 1720: | <nt def="NT-choice">choice</nt>
! 1721: | <nt def="NT-seq">seq</nt>)
! 1722: ('?' | '*' | '+')?</rhs></prod>
! 1723: <prod id="NT-choice"><lhs>choice</lhs>
! 1724: <rhs>'(' <nt def="NT-S">S</nt>? cp
! 1725: ( <nt def="NT-S">S</nt>? '|' <nt def="NT-S">S</nt>? <nt def="NT-cp">cp</nt> )*
! 1726: <nt def="NT-S">S</nt>? ')'</rhs>
! 1727: <vc def="vc-PEinGroup"/></prod>
! 1728: <prod id="NT-seq"><lhs>seq</lhs>
! 1729: <rhs>'(' <nt def="NT-S">S</nt>? cp
! 1730: ( <nt def="NT-S">S</nt>? ',' <nt def="NT-S">S</nt>? <nt def="NT-cp">cp</nt> )*
! 1731: <nt def="NT-S">S</nt>? ')'</rhs>
! 1732: <vc def="vc-PEinGroup"/></prod>
! 1733:
! 1734: </prodgroup>
! 1735: </scrap>
! 1736: where each <nt def="NT-Name">Name</nt> is the type of an element which may
! 1737: appear as a <termref def="dt-parentchild">child</termref>.
! 1738: Any content
! 1739: particle in a choice list may appear in the <termref def="dt-elemcontent">element content</termref> at the location where
! 1740: the choice list appears in the grammar;
! 1741: content particles occurring in a sequence list must each
! 1742: appear in the <termref def="dt-elemcontent">element content</termref> in the
! 1743: order given in the list.
! 1744: The optional character following a name or list governs
! 1745: whether the element or the content particles in the list may occur one
! 1746: or more (<code>+</code>), zero or more (<code>*</code>), or zero or
! 1747: one times (<code>?</code>).
! 1748: The absence of such an operator means that the element or content particle
! 1749: must appear exactly once.
! 1750: This syntax
! 1751: and meaning are identical to those used in the productions in this
! 1752: specification.</p>
! 1753: <p>
! 1754: The content of an element matches a content model if and only if it is
! 1755: possible to trace out a path through the content model, obeying the
! 1756: sequence, choice, and repetition operators and matching each element in
! 1757: the content against an element type in the content model. <termref def="dt-compat">For compatibility</termref>, it is an error
! 1758: if an element in the document can
! 1759: match more than one occurrence of an element type in the content model.
! 1760: For more information, see <specref ref="determinism"/>.
! 1761: <!-- appendix <specref ref="determinism"/>. -->
! 1762: <!-- appendix on deterministic content models. -->
! 1763: </p>
! 1764: <vcnote id="vc-PEinGroup">
! 1765: <head>Proper Group/PE Nesting</head>
! 1766: <p>Parameter-entity
! 1767: <termref def="dt-repltext">replacement text</termref> must be properly nested
! 1768: with parenthetized groups.
! 1769: That is to say, if either of the opening or closing parentheses
! 1770: in a <nt def="NT-choice">choice</nt>, <nt def="NT-seq">seq</nt>, or
! 1771: <nt def="NT-Mixed">Mixed</nt> construct
! 1772: is contained in the replacement text for a
! 1773: <termref def="dt-PERef">parameter entity</termref>,
! 1774: both must be contained in the same replacement text.</p>
! 1775: <p><termref def="dt-interop">For interoperability</termref>,
! 1776: if a parameter-entity reference appears in a
! 1777: <nt def="NT-choice">choice</nt>, <nt def="NT-seq">seq</nt>, or
! 1778: <nt def="NT-Mixed">Mixed</nt> construct, its replacement text
! 1779: should not be empty, and
! 1780: neither the first nor last non-blank
! 1781: character of the replacement text should be a connector
! 1782: (<code>|</code> or <code>,</code>).
! 1783: </p>
! 1784: </vcnote>
! 1785: <p>Examples of element-content models:
! 1786: <eg><!ELEMENT spec (front, body, back?)>
! 1787: <!ELEMENT div1 (head, (p | list | note)*, div2*)>
! 1788: <!ELEMENT dictionary-body (%div.mix; | %dict.mix;)*></eg></p>
! 1789: </div3>
! 1790:
! 1791: <div3 id="sec-mixed-content">
! 1792: <head>Mixed Content</head>
! 1793:
! 1794: <p><termdef id="dt-mixed" term="Mixed Content">An element
! 1795: <termref def="dt-stag">type</termref> has
! 1796: <term>mixed content</term> when elements of that type may contain
! 1797: character data, optionally interspersed with
! 1798: <termref def="dt-parentchild">child</termref> elements.</termdef>
! 1799: In this case, the types of the child elements
! 1800: may be constrained, but not their order or their number of occurrences:
! 1801: <scrap lang="ebnf">
! 1802: <head>Mixed-content Declaration</head>
! 1803: <prodgroup pcw2="5.5" pcw4="16" pcw5="11">
! 1804: <prod id="NT-Mixed"><lhs>Mixed</lhs>
! 1805: <rhs>'(' <nt def="NT-S">S</nt>?
! 1806: '#PCDATA'
! 1807: (<nt def="NT-S">S</nt>?
! 1808: '|'
! 1809: <nt def="NT-S">S</nt>?
! 1810: <nt def="NT-Name">Name</nt>)*
! 1811: <nt def="NT-S">S</nt>?
! 1812: ')*' </rhs>
! 1813: <rhs>| '(' <nt def="NT-S">S</nt>? '#PCDATA' <nt def="NT-S">S</nt>? ')'
! 1814: </rhs><vc def="vc-PEinGroup"/>
! 1815: <vc def="vc-MixedChildrenUnique"/>
! 1816: </prod>
! 1817:
! 1818: </prodgroup>
! 1819: </scrap>
! 1820: where the <nt def="NT-Name">Name</nt>s give the types of elements
! 1821: that may appear as children.
! 1822: </p>
! 1823: <vcnote id="vc-MixedChildrenUnique">
! 1824: <head>No Duplicate Types</head>
! 1825: <p>The same name must not appear more than once in a single mixed-content
! 1826: declaration.
! 1827: </p></vcnote>
! 1828: <p>Examples of mixed content declarations:
! 1829: <eg><!ELEMENT p (#PCDATA|a|ul|b|i|em)*>
! 1830: <!ELEMENT p (#PCDATA | %font; | %phrase; | %special; | %form;)* >
! 1831: <!ELEMENT b (#PCDATA)></eg></p>
! 1832: </div3>
! 1833: </div2>
! 1834:
! 1835: <div2 id="attdecls">
! 1836: <head>Attribute-List Declarations</head>
! 1837:
! 1838: <p><termref def="dt-attr">Attributes</termref> are used to associate
! 1839: name-value pairs with <termref def="dt-element">elements</termref>.
! 1840: Attribute specifications may appear only within <termref def="dt-stag">start-tags</termref>
! 1841: and <termref def="dt-eetag">empty-element tags</termref>;
! 1842: thus, the productions used to
! 1843: recognize them appear in <specref ref="sec-starttags"/>.
! 1844: Attribute-list
! 1845: declarations may be used:
! 1846: <ulist>
! 1847: <item><p>To define the set of attributes pertaining to a given
! 1848: element type.</p></item>
! 1849: <item><p>To establish type constraints for these
! 1850: attributes.</p></item>
! 1851: <item><p>To provide <termref def="dt-default">default values</termref>
! 1852: for attributes.</p></item>
! 1853: </ulist>
! 1854: </p>
! 1855: <p><termdef id="dt-attdecl" term="Attribute-List Declaration">
! 1856: <term>Attribute-list declarations</term> specify the name, data type, and default
! 1857: value (if any) of each attribute associated with a given element type:
! 1858: <scrap lang="ebnf">
! 1859: <head>Attribute-list Declaration</head>
! 1860: <prod id="NT-AttlistDecl"><lhs>AttlistDecl</lhs>
! 1861: <rhs>'<!ATTLIST' <nt def="NT-S">S</nt>
! 1862: <nt def="NT-Name">Name</nt>
! 1863: <nt def="NT-AttDef">AttDef</nt>*
! 1864: <nt def="NT-S">S</nt>? '>'</rhs>
! 1865: </prod>
! 1866: <prod id="NT-AttDef"><lhs>AttDef</lhs>
! 1867: <rhs><nt def="NT-S">S</nt> <nt def="NT-Name">Name</nt>
! 1868: <nt def="NT-S">S</nt> <nt def="NT-AttType">AttType</nt>
! 1869: <nt def="NT-S">S</nt> <nt def="NT-DefaultDecl">DefaultDecl</nt></rhs>
! 1870: </prod>
! 1871: </scrap>
! 1872: The <nt def="NT-Name">Name</nt> in the
! 1873: <nt def="NT-AttlistDecl">AttlistDecl</nt> rule is the type of an element. At
! 1874: user option, an XML processor may issue a warning if attributes are
! 1875: declared for an element type not itself declared, but this is not an
! 1876: error. The <nt def="NT-Name">Name</nt> in the
! 1877: <nt def="NT-AttDef">AttDef</nt> rule is
! 1878: the name of the attribute.</termdef></p>
! 1879: <p>
! 1880: When more than one <nt def="NT-AttlistDecl">AttlistDecl</nt> is provided for a
! 1881: given element type, the contents of all those provided are merged. When
! 1882: more than one definition is provided for the same attribute of a
! 1883: given element type, the first declaration is binding and later
! 1884: declarations are ignored.
! 1885: <termref def="dt-interop">For interoperability,</termref> writers of DTDs
! 1886: may choose to provide at most one attribute-list declaration
! 1887: for a given element type, at most one attribute definition
! 1888: for a given attribute name, and at least one attribute definition
! 1889: in each attribute-list declaration.
! 1890: For interoperability, an XML processor may at user option
! 1891: issue a warning when more than one attribute-list declaration is
! 1892: provided for a given element type, or more than one attribute definition
! 1893: is provided
! 1894: for a given attribute, but this is not an error.
! 1895: </p>
! 1896:
! 1897: <div3 id="sec-attribute-types">
! 1898: <head>Attribute Types</head>
! 1899:
! 1900: <p>XML attribute types are of three kinds: a string type, a
! 1901: set of tokenized types, and enumerated types. The string type may take
! 1902: any literal string as a value; the tokenized types have varying lexical
! 1903: and semantic constraints, as noted:
! 1904: <scrap lang="ebnf">
! 1905: <head>Attribute Types</head>
! 1906: <prodgroup pcw4="14" pcw5="11.5">
! 1907: <prod id="NT-AttType"><lhs>AttType</lhs>
! 1908: <rhs><nt def="NT-StringType">StringType</nt>
! 1909: | <nt def="NT-TokenizedType">TokenizedType</nt>
! 1910: | <nt def="NT-EnumeratedType">EnumeratedType</nt>
! 1911: </rhs>
! 1912: </prod>
! 1913: <prod id="NT-StringType"><lhs>StringType</lhs>
! 1914: <rhs>'CDATA'</rhs>
! 1915: </prod>
! 1916: <prod id="NT-TokenizedType"><lhs>TokenizedType</lhs>
! 1917: <rhs>'ID'</rhs>
! 1918: <vc def="id"/>
! 1919: <vc def="one-id-per-el"/>
! 1920: <vc def="id-default"/>
! 1921: <rhs>| 'IDREF'</rhs>
! 1922: <vc def="idref"/>
! 1923: <rhs>| 'IDREFS'</rhs>
! 1924: <vc def="idref"/>
! 1925: <rhs>| 'ENTITY'</rhs>
! 1926: <vc def="entname"/>
! 1927: <rhs>| 'ENTITIES'</rhs>
! 1928: <vc def="entname"/>
! 1929: <rhs>| 'NMTOKEN'</rhs>
! 1930: <vc def="nmtok"/>
! 1931: <rhs>| 'NMTOKENS'</rhs>
! 1932: <vc def="nmtok"/></prod>
! 1933: </prodgroup>
! 1934: </scrap>
! 1935: </p>
! 1936: <vcnote id="id">
! 1937: <head>ID</head>
! 1938: <p>
! 1939: Values of type <kw>ID</kw> must match the
! 1940: <nt def="NT-Name">Name</nt> production.
! 1941: A name must not appear more than once in
! 1942: an XML document as a value of this type; i.e., ID values must uniquely
! 1943: identify the elements which bear them.
! 1944: </p>
! 1945: </vcnote>
! 1946: <vcnote id="one-id-per-el">
! 1947: <head>One ID per Element Type</head>
! 1948: <p>No element type may have more than one ID attribute specified.</p>
! 1949: </vcnote>
! 1950: <vcnote id="id-default">
! 1951: <head>ID Attribute Default</head>
! 1952: <p>An ID attribute must have a declared default of <kw>#IMPLIED</kw> or
! 1953: <kw>#REQUIRED</kw>.</p>
! 1954: </vcnote>
! 1955: <vcnote id="idref">
! 1956: <head>IDREF</head>
! 1957: <p>
! 1958: Values of type <kw>IDREF</kw> must match
! 1959: the <nt def="NT-Name">Name</nt> production, and
! 1960: values of type <kw>IDREFS</kw> must match
! 1961: <nt def="NT-Names">Names</nt>;
! 1962: each <nt def="NT-Name">Name</nt> must match the value of an ID attribute on
! 1963: some element in the XML document; i.e. <kw>IDREF</kw> values must
! 1964: match the value of some ID attribute.
! 1965: </p>
! 1966: </vcnote>
! 1967: <vcnote id="entname">
! 1968: <head>Entity Name</head>
! 1969: <p>
! 1970: Values of type <kw>ENTITY</kw>
! 1971: must match the <nt def="NT-Name">Name</nt> production,
! 1972: values of type <kw>ENTITIES</kw> must match
! 1973: <nt def="NT-Names">Names</nt>;
! 1974: each <nt def="NT-Name">Name</nt> must
! 1975: match the
! 1976: name of an <termref def="dt-unparsed">unparsed entity</termref> declared in the
! 1977: <termref def="dt-doctype">DTD</termref>.
! 1978: </p>
! 1979: </vcnote>
! 1980: <vcnote id="nmtok">
! 1981: <head>Name Token</head>
! 1982: <p>
! 1983: Values of type <kw>NMTOKEN</kw> must match the
! 1984: <nt def="NT-Nmtoken">Nmtoken</nt> production;
! 1985: values of type <kw>NMTOKENS</kw> must
! 1986: match <termref def="NT-Nmtokens">Nmtokens</termref>.
! 1987: </p>
! 1988: </vcnote>
! 1989: <!-- why?
! 1990: <p>The XML processor must normalize attribute values before
! 1991: passing them to the application, as described in
! 1992: <specref ref="AVNormalize"/>.</p>-->
! 1993: <p><termdef id="dt-enumerated" term="Enumerated Attribute Values"><term>Enumerated attributes</term> can take one
! 1994: of a list of values provided in the declaration</termdef>. There are two
! 1995: kinds of enumerated types:
! 1996: <scrap lang="ebnf">
! 1997: <head>Enumerated Attribute Types</head>
! 1998: <prod id="NT-EnumeratedType"><lhs>EnumeratedType</lhs>
! 1999: <rhs><nt def="NT-NotationType">NotationType</nt>
! 2000: | <nt def="NT-Enumeration">Enumeration</nt>
! 2001: </rhs></prod>
! 2002: <prod id="NT-NotationType"><lhs>NotationType</lhs>
! 2003: <rhs>'NOTATION'
! 2004: <nt def="NT-S">S</nt>
! 2005: '('
! 2006: <nt def="NT-S">S</nt>?
! 2007: <nt def="NT-Name">Name</nt>
! 2008: (<nt def="NT-S">S</nt>? '|' <nt def="NT-S">S</nt>?
! 2009: <nt def="NT-Name">Name</nt>)*
! 2010: <nt def="NT-S">S</nt>? ')'
! 2011: </rhs>
! 2012: <vc def="notatn"/></prod>
! 2013: <prod id="NT-Enumeration"><lhs>Enumeration</lhs>
! 2014: <rhs>'(' <nt def="NT-S">S</nt>?
! 2015: <nt def="NT-Nmtoken">Nmtoken</nt>
! 2016: (<nt def="NT-S">S</nt>? '|'
! 2017: <nt def="NT-S">S</nt>?
! 2018: <nt def="NT-Nmtoken">Nmtoken</nt>)*
! 2019: <nt def="NT-S">S</nt>?
! 2020: ')'</rhs>
! 2021: <vc def="enum"/></prod>
! 2022: </scrap>
! 2023: A <kw>NOTATION</kw> attribute identifies a
! 2024: <termref def="dt-notation">notation</termref>, declared in the
! 2025: DTD with associated system and/or public identifiers, to
! 2026: be used in interpreting the element to which the attribute
! 2027: is attached.
! 2028: </p>
! 2029:
! 2030: <vcnote id="notatn">
! 2031: <head>Notation Attributes</head>
! 2032: <p>
! 2033: Values of this type must match
! 2034: one of the <titleref href="Notations">notation</titleref> names included in
! 2035: the declaration; all notation names in the declaration must
! 2036: be declared.
! 2037: </p>
! 2038: </vcnote>
! 2039: <vcnote id="enum">
! 2040: <head>Enumeration</head>
! 2041: <p>
! 2042: Values of this type
! 2043: must match one of the <nt def="NT-Nmtoken">Nmtoken</nt> tokens in the
! 2044: declaration.
! 2045: </p>
! 2046: </vcnote>
! 2047: <p><termref def="dt-interop">For interoperability,</termref> the same
! 2048: <nt def="NT-Nmtoken">Nmtoken</nt> should not occur more than once in the
! 2049: enumerated attribute types of a single element type.
! 2050: </p>
! 2051: </div3>
! 2052:
! 2053: <div3 id="sec-attr-defaults">
! 2054: <head>Attribute Defaults</head>
! 2055:
! 2056: <p>An <termref def="dt-attdecl">attribute declaration</termref> provides
! 2057: information on whether
! 2058: the attribute's presence is required, and if not, how an XML processor should
! 2059: react if a declared attribute is absent in a document.
! 2060: <scrap lang="ebnf">
! 2061: <head>Attribute Defaults</head>
! 2062: <prodgroup pcw4="14" pcw5="11.5">
! 2063: <prod id="NT-DefaultDecl"><lhs>DefaultDecl</lhs>
! 2064: <rhs>'#REQUIRED'
! 2065: | '#IMPLIED' </rhs>
! 2066: <rhs>| (('#FIXED' S)? <nt def="NT-AttValue">AttValue</nt>)</rhs>
! 2067: <vc def="RequiredAttr"/>
! 2068: <vc def="defattrvalid"/>
! 2069: <wfc def="CleanAttrVals"/>
! 2070: <vc def="FixedAttr"/>
! 2071: </prod>
! 2072: </prodgroup>
! 2073: </scrap>
! 2074:
! 2075: </p>
! 2076: <p>In an attribute declaration, <kw>#REQUIRED</kw> means that the
! 2077: attribute must always be provided, <kw>#IMPLIED</kw> that no default
! 2078: value is provided.
! 2079: <!-- not any more!!
! 2080: <kw>#IMPLIED</kw> means that if the attribute is omitted
! 2081: from an element of this type,
! 2082: the XML processor must inform the application
! 2083: that no value was specified; no constraint is placed on the behavior
! 2084: of the application. -->
! 2085: <termdef id="dt-default" term="Attribute Default">If the
! 2086: declaration
! 2087: is neither <kw>#REQUIRED</kw> nor <kw>#IMPLIED</kw>, then the
! 2088: <nt def="NT-AttValue">AttValue</nt> value contains the declared
! 2089: <term>default</term> value; the <kw>#FIXED</kw> keyword states that
! 2090: the attribute must always have the default value.
! 2091: If a default value
! 2092: is declared, when an XML processor encounters an omitted attribute, it
! 2093: is to behave as though the attribute were present with
! 2094: the declared default value.</termdef></p>
! 2095: <vcnote id="RequiredAttr">
! 2096: <head>Required Attribute</head>
! 2097: <p>If the default declaration is the keyword <kw>#REQUIRED</kw>, then
! 2098: the attribute must be specified for
! 2099: all elements of the type in the attribute-list declaration.
! 2100: </p></vcnote>
! 2101: <vcnote id="defattrvalid">
! 2102: <head>Attribute Default Legal</head>
! 2103: <p>
! 2104: The declared
! 2105: default value must meet the lexical constraints of the declared attribute type.
! 2106: </p>
! 2107: </vcnote>
! 2108: <vcnote id="FixedAttr">
! 2109: <head>Fixed Attribute Default</head>
! 2110: <p>If an attribute has a default value declared with the
! 2111: <kw>#FIXED</kw> keyword, instances of that attribute must
! 2112: match the default value.
! 2113: </p></vcnote>
! 2114:
! 2115: <p>Examples of attribute-list declarations:
! 2116: <eg><!ATTLIST termdef
! 2117: id ID #REQUIRED
! 2118: name CDATA #IMPLIED>
! 2119: <!ATTLIST list
! 2120: type (bullets|ordered|glossary) "ordered">
! 2121: <!ATTLIST form
! 2122: method CDATA #FIXED "POST"></eg></p>
! 2123: </div3>
! 2124: <div3 id="AVNormalize">
! 2125: <head>Attribute-Value Normalization</head>
! 2126: <p>Before the value of an attribute is passed to the application
! 2127: or checked for validity, the
! 2128: XML processor must normalize it as follows:
! 2129: <ulist>
! 2130: <item><p>a character reference is processed by appending the referenced
! 2131: character to the attribute value</p></item>
! 2132: <item><p>an entity reference is processed by recursively processing the
! 2133: replacement text of the entity</p></item>
! 2134: <item><p>a whitespace character (#x20, #xD, #xA, #x9) is processed by
! 2135: appending #x20 to the normalized value, except that only a single #x20
! 2136: is appended for a "#xD#xA" sequence that is part of an external
! 2137: parsed entity or the literal entity value of an internal parsed
! 2138: entity</p></item>
! 2139: <item><p>other characters are processed by appending them to the normalized
! 2140: value</p>
! 2141: </item></ulist>
! 2142: </p>
! 2143: <p>If the declared value is not CDATA, then the XML processor must
! 2144: further process the normalized attribute value by discarding any
! 2145: leading and trailing space (#x20) characters, and by replacing
! 2146: sequences of space (#x20) characters by a single space (#x20)
! 2147: character.</p>
! 2148: <p>
! 2149: All attributes for which no declaration has been read should be treated
! 2150: by a non-validating parser as if declared
! 2151: <kw>CDATA</kw>.
! 2152: </p>
! 2153: </div3>
! 2154: </div2>
! 2155: <div2 id="sec-condition-sect">
! 2156: <head>Conditional Sections</head>
! 2157: <p><termdef id="dt-cond-section" term="conditional section">
! 2158: <term>Conditional sections</term> are portions of the
! 2159: <termref def="dt-doctype">document type declaration external subset</termref>
! 2160: which are
! 2161: included in, or excluded from, the logical structure of the DTD based on
! 2162: the keyword which governs them.</termdef>
! 2163: <scrap lang="ebnf">
! 2164: <head>Conditional Section</head>
! 2165: <prodgroup pcw2="9" pcw4="14.5">
! 2166: <prod id="NT-conditionalSect"><lhs>conditionalSect</lhs>
! 2167: <rhs><nt def="NT-includeSect">includeSect</nt>
! 2168: | <nt def="NT-ignoreSect">ignoreSect</nt>
! 2169: </rhs>
! 2170: </prod>
! 2171: <prod id="NT-includeSect"><lhs>includeSect</lhs>
! 2172: <rhs>'<![' S? 'INCLUDE' S? '['
! 2173:
! 2174: <nt def="NT-extSubsetDecl">extSubsetDecl</nt>
! 2175: ']]>'
! 2176: </rhs>
! 2177: </prod>
! 2178: <prod id="NT-ignoreSect"><lhs>ignoreSect</lhs>
! 2179: <rhs>'<![' S? 'IGNORE' S? '['
! 2180: <nt def="NT-ignoreSectContents">ignoreSectContents</nt>*
! 2181: ']]>'</rhs>
! 2182: </prod>
! 2183:
! 2184: <prod id="NT-ignoreSectContents"><lhs>ignoreSectContents</lhs>
! 2185: <rhs><nt def="NT-Ignore">Ignore</nt>
! 2186: ('<![' <nt def="NT-ignoreSectContents">ignoreSectContents</nt> ']]>'
! 2187: <nt def="NT-Ignore">Ignore</nt>)*</rhs></prod>
! 2188: <prod id="NT-Ignore"><lhs>Ignore</lhs>
! 2189: <rhs><nt def="NT-Char">Char</nt>* -
! 2190: (<nt def="NT-Char">Char</nt>* ('<![' | ']]>')
! 2191: <nt def="NT-Char">Char</nt>*)
! 2192: </rhs></prod>
! 2193:
! 2194: </prodgroup>
! 2195: </scrap>
! 2196: </p>
! 2197: <p>Like the internal and external DTD subsets, a conditional section
! 2198: may contain one or more complete declarations,
! 2199: comments, processing instructions,
! 2200: or nested conditional sections, intermingled with white space.
! 2201: </p>
! 2202: <p>If the keyword of the
! 2203: conditional section is <kw>INCLUDE</kw>, then the contents of the conditional
! 2204: section are part of the DTD.
! 2205: If the keyword of the conditional
! 2206: section is <kw>IGNORE</kw>, then the contents of the conditional section are
! 2207: not logically part of the DTD.
! 2208: Note that for reliable parsing, the contents of even ignored
! 2209: conditional sections must be read in order to
! 2210: detect nested conditional sections and ensure that the end of the
! 2211: outermost (ignored) conditional section is properly detected.
! 2212: If a conditional section with a
! 2213: keyword of <kw>INCLUDE</kw> occurs within a larger conditional
! 2214: section with a keyword of <kw>IGNORE</kw>, both the outer and the
! 2215: inner conditional sections are ignored.</p>
! 2216: <p>If the keyword of the conditional section is a
! 2217: parameter-entity reference, the parameter entity must be replaced by its
! 2218: content before the processor decides whether to
! 2219: include or ignore the conditional section.</p>
! 2220: <p>An example:
! 2221: <eg><!ENTITY % draft 'INCLUDE' >
! 2222: <!ENTITY % final 'IGNORE' >
! 2223:
! 2224: <![%draft;[
! 2225: <!ELEMENT book (comments*, title, body, supplements?)>
! 2226: ]]>
! 2227: <![%final;[
! 2228: <!ELEMENT book (title, body, supplements?)>
! 2229: ]]>
! 2230: </eg>
! 2231: </p>
! 2232: </div2>
! 2233:
! 2234:
! 2235: <!--
! 2236: <div2 id='sec-pass-to-app'>
! 2237: <head>XML Processor Treatment of Logical Structure</head>
! 2238: <p>When an XML processor encounters a start-tag, it must make
! 2239: at least the following information available to the application:
! 2240: <ulist>
! 2241: <item>
! 2242: <p>the element type's generic identifier</p>
! 2243: </item>
! 2244: <item>
! 2245: <p>the names of attributes known to apply to this element type
! 2246: (validating processors must make available names of all attributes
! 2247: declared for the element type; non-validating processors must
! 2248: make available at least the names of the attributes for which
! 2249: values are specified.
! 2250: </p>
! 2251: </item>
! 2252: </ulist>
! 2253: </p>
! 2254: </div2>
! 2255: -->
! 2256:
! 2257: </div1>
! 2258: <!-- &Entities; -->
! 2259:
! 2260: <div1 id="sec-physical-struct">
! 2261: <head>Physical Structures</head>
! 2262:
! 2263: <p><termdef id="dt-entity" term="Entity">An XML document may consist
! 2264: of one or many storage units. These are called
! 2265: <term>entities</term>; they all have <term>content</term> and are all
! 2266: (except for the document entity, see below, and
! 2267: the <termref def="dt-doctype">external DTD subset</termref>)
! 2268: identified by <term>name</term>.
! 2269: </termdef>
! 2270: Each XML document has one entity
! 2271: called the <termref def="dt-docent">document entity</termref>, which serves
! 2272: as the starting point for the <termref def="dt-xml-proc">XML
! 2273: processor</termref> and may contain the whole document.</p>
! 2274: <p>Entities may be either parsed or unparsed.
! 2275: <termdef id="dt-parsedent" term="Text Entity">A <term>parsed entity's</term>
! 2276: contents are referred to as its
! 2277: <termref def="dt-repltext">replacement text</termref>;
! 2278: this <termref def="dt-text">text</termref> is considered an
! 2279: integral part of the document.</termdef></p>
! 2280:
! 2281: <p><termdef id="dt-unparsed" term="Unparsed Entity">An
! 2282: <term>unparsed entity</term>
! 2283: is a resource whose contents may or may not be
! 2284: <termref def="dt-text">text</termref>, and if text, may not be XML.
! 2285: Each unparsed entity
! 2286: has an associated <termref def="dt-notation">notation</termref>, identified by name.
! 2287: Beyond a requirement
! 2288: that an XML processor make the identifiers for the entity and
! 2289: notation available to the application,
! 2290: XML places no constraints on the contents of unparsed entities.</termdef>
! 2291: </p>
! 2292: <p>
! 2293: Parsed entities are invoked by name using entity references;
! 2294: unparsed entities by name, given in the value of <kw>ENTITY</kw>
! 2295: or <kw>ENTITIES</kw>
! 2296: attributes.</p>
! 2297: <p><termdef id="gen-entity" term="general entity"><term>General entities</term>
! 2298: are entities for use within the document content.
! 2299: In this specification, general entities are sometimes referred
! 2300: to with the unqualified term <emph>entity</emph> when this leads
! 2301: to no ambiguity.</termdef>
! 2302: <termdef id="dt-PE" term="Parameter entity">Parameter entities
! 2303: are parsed entities for use within the DTD.</termdef>
! 2304: These two types of entities use different forms of reference and
! 2305: are recognized in different contexts.
! 2306: Furthermore, they occupy different namespaces; a parameter entity and
! 2307: a general entity with the same name are two distinct entities.
! 2308: </p>
! 2309:
! 2310: <div2 id="sec-references">
! 2311: <head>Character and Entity References</head>
! 2312: <p><termdef id="dt-charref" term="Character Reference">
! 2313: A <term>character reference</term> refers to a specific character in the
! 2314: ISO/IEC 10646 character set, for example one not directly accessible from
! 2315: available input devices.
! 2316: <scrap lang="ebnf">
! 2317: <head>Character Reference</head>
! 2318: <prod id="NT-CharRef"><lhs>CharRef</lhs>
! 2319: <rhs>'&#' [0-9]+ ';' </rhs>
! 2320: <rhs>| '&hcro;' [0-9a-fA-F]+ ';'</rhs>
! 2321: <wfc def="wf-Legalchar"/>
! 2322: </prod>
! 2323: </scrap>
! 2324: <wfcnote id="wf-Legalchar">
! 2325: <head>Legal Character</head>
! 2326: <p>Characters referred to using character references must
! 2327: match the production for
! 2328: <termref def="NT-Char">Char</termref>.</p>
! 2329: </wfcnote>
! 2330: If the character reference begins with "<code>&#x</code>", the digits and
! 2331: letters up to the terminating <code>;</code> provide a hexadecimal
! 2332: representation of the character's code point in ISO/IEC 10646.
! 2333: If it begins just with "<code>&#</code>", the digits up to the terminating
! 2334: <code>;</code> provide a decimal representation of the character's
! 2335: code point.
! 2336: </termdef>
! 2337: </p>
! 2338: <p><termdef id="dt-entref" term="Entity Reference">An <term>entity
! 2339: reference</term> refers to the content of a named entity.</termdef>
! 2340: <termdef id="dt-GERef" term="General Entity Reference">References to
! 2341: parsed general entities
! 2342: use ampersand (<code>&</code>) and semicolon (<code>;</code>) as
! 2343: delimiters.</termdef>
! 2344: <termdef id="dt-PERef" term="Parameter-entity reference">
! 2345: <term>Parameter-entity references</term> use percent-sign (<code>%</code>) and
! 2346: semicolon
! 2347: (<code>;</code>) as delimiters.</termdef>
! 2348: </p>
! 2349: <scrap lang="ebnf">
! 2350: <head>Entity Reference</head>
! 2351: <prod id="NT-Reference"><lhs>Reference</lhs>
! 2352: <rhs><nt def="NT-EntityRef">EntityRef</nt>
! 2353: | <nt def="NT-CharRef">CharRef</nt></rhs></prod>
! 2354: <prod id="NT-EntityRef"><lhs>EntityRef</lhs>
! 2355: <rhs>'&' <nt def="NT-Name">Name</nt> ';'</rhs>
! 2356: <wfc def="wf-entdeclared"/>
! 2357: <vc def="vc-entdeclared"/>
! 2358: <wfc def="textent"/>
! 2359: <wfc def="norecursion"/>
! 2360: </prod>
! 2361: <prod id="NT-PEReference"><lhs>PEReference</lhs>
! 2362: <rhs>'%' <nt def="NT-Name">Name</nt> ';'</rhs>
! 2363: <vc def="vc-entdeclared"/>
! 2364: <wfc def="norecursion"/>
! 2365: <wfc def="indtd"/>
! 2366: </prod>
! 2367: </scrap>
! 2368:
! 2369: <wfcnote id="wf-entdeclared">
! 2370: <head>Entity Declared</head>
! 2371: <p>In a document without any DTD, a document with only an internal
! 2372: DTD subset which contains no parameter entity references, or a document with
! 2373: "<code>standalone='yes'</code>",
! 2374: the <nt def="NT-Name">Name</nt> given in the entity reference must
! 2375: <termref def="dt-match">match</termref> that in an
! 2376: <titleref href="sec-entity-decl">entity declaration</titleref>, except that
! 2377: well-formed documents need not declare
! 2378: any of the following entities: &magicents;.
! 2379: The declaration of a parameter entity must precede any reference to it.
! 2380: Similarly, the declaration of a general entity must precede any
! 2381: reference to it which appears in a default value in an attribute-list
! 2382: declaration.</p>
! 2383: <p>Note that if entities are declared in the external subset or in
! 2384: external parameter entities, a non-validating processor is
! 2385: <titleref href="include-if-valid">not obligated to</titleref> read
! 2386: and process their declarations; for such documents, the rule that
! 2387: an entity must be declared is a well-formedness constraint only
! 2388: if <titleref href="sec-rmd">standalone='yes'</titleref>.</p>
! 2389: </wfcnote>
! 2390: <vcnote id="vc-entdeclared">
! 2391: <head>Entity Declared</head>
! 2392: <p>In a document with an external subset or external parameter
! 2393: entities with "<code>standalone='no'</code>",
! 2394: the <nt def="NT-Name">Name</nt> given in the entity reference must <termref def="dt-match">match</termref> that in an
! 2395: <titleref href="sec-entity-decl">entity declaration</titleref>.
! 2396: For interoperability, valid documents should declare the entities
! 2397: &magicents;, in the form
! 2398: specified in <specref ref="sec-predefined-ent"/>.
! 2399: The declaration of a parameter entity must precede any reference to it.
! 2400: Similarly, the declaration of a general entity must precede any
! 2401: reference to it which appears in a default value in an attribute-list
! 2402: declaration.</p>
! 2403: </vcnote>
! 2404: <!-- FINAL EDIT: is this duplication too clumsy? -->
! 2405: <wfcnote id="textent">
! 2406: <head>Parsed Entity</head>
! 2407: <p>
! 2408: An entity reference must not contain the name of an <termref def="dt-unparsed">unparsed entity</termref>. Unparsed entities may be referred
! 2409: to only in <termref def="dt-attrval">attribute values</termref> declared to
! 2410: be of type <kw>ENTITY</kw> or <kw>ENTITIES</kw>.
! 2411: </p>
! 2412: </wfcnote>
! 2413: <wfcnote id="norecursion">
! 2414: <head>No Recursion</head>
! 2415: <p>
! 2416: A parsed entity must not contain a recursive reference to itself,
! 2417: either directly or indirectly.
! 2418: </p>
! 2419: </wfcnote>
! 2420: <wfcnote id="indtd">
! 2421: <head>In DTD</head>
! 2422: <p>
! 2423: Parameter-entity references may only appear in the
! 2424: <termref def="dt-doctype">DTD</termref>.
! 2425: </p>
! 2426: </wfcnote>
! 2427: <p>Examples of character and entity references:
! 2428: <eg>Type <key>less-than</key> (&hcro;3C;) to save options.
! 2429: This document was prepared on &docdate; and
! 2430: is classified &security-level;.</eg></p>
! 2431: <p>Example of a parameter-entity reference:
! 2432: <eg><![CDATA[<!-- declare the parameter entity "ISOLat2"... -->
! 2433: <!ENTITY % ISOLat2
! 2434: SYSTEM "http://www.xml.com/iso/isolat2-xml.entities" >
! 2435: <!-- ... now reference it. -->
! 2436: %ISOLat2;]]></eg></p>
! 2437: </div2>
! 2438:
! 2439: <div2 id="sec-entity-decl">
! 2440: <head>Entity Declarations</head>
! 2441:
! 2442: <p><termdef id="dt-entdecl" term="entity declaration">
! 2443: Entities are declared thus:
! 2444: <scrap lang="ebnf">
! 2445: <head>Entity Declaration</head>
! 2446: <prodgroup pcw2="5" pcw4="18.5">
! 2447: <prod id="NT-EntityDecl"><lhs>EntityDecl</lhs>
! 2448: <rhs><nt def="NT-GEDecl">GEDecl</nt><!--</rhs><com>General entities</com>
! 2449: <rhs>--> | <nt def="NT-PEDecl">PEDecl</nt></rhs>
! 2450: <!--<com>Parameter entities</com>-->
! 2451: </prod>
! 2452: <prod id="NT-GEDecl"><lhs>GEDecl</lhs>
! 2453: <rhs>'<!ENTITY' <nt def="NT-S">S</nt> <nt def="NT-Name">Name</nt>
! 2454: <nt def="NT-S">S</nt> <nt def="NT-EntityDef">EntityDef</nt>
! 2455: <nt def="NT-S">S</nt>? '>'</rhs>
! 2456: </prod>
! 2457: <prod id="NT-PEDecl"><lhs>PEDecl</lhs>
! 2458: <rhs>'<!ENTITY' <nt def="NT-S">S</nt> '%' <nt def="NT-S">S</nt>
! 2459: <nt def="NT-Name">Name</nt> <nt def="NT-S">S</nt>
! 2460: <nt def="NT-PEDef">PEDef</nt> <nt def="NT-S">S</nt>? '>'</rhs>
! 2461: <!--<com>Parameter entities</com>-->
! 2462: </prod>
! 2463: <prod id="NT-EntityDef"><lhs>EntityDef</lhs>
! 2464: <rhs><nt def="NT-EntityValue">EntityValue</nt>
! 2465: <!--</rhs>
! 2466: <rhs>-->| (<nt def="NT-ExternalID">ExternalID</nt>
! 2467: <nt def="NT-NDataDecl">NDataDecl</nt>?)</rhs>
! 2468: <!-- <nt def='NT-ExternalDef'>ExternalDef</nt></rhs> -->
! 2469: </prod>
! 2470: <!-- FINAL EDIT: what happened to WFs here? -->
! 2471: <prod id="NT-PEDef"><lhs>PEDef</lhs>
! 2472: <rhs><nt def="NT-EntityValue">EntityValue</nt>
! 2473: | <nt def="NT-ExternalID">ExternalID</nt></rhs></prod>
! 2474: </prodgroup>
! 2475: </scrap>
! 2476: The <nt def="NT-Name">Name</nt> identifies the entity in an
! 2477: <termref def="dt-entref">entity reference</termref> or, in the case of an
! 2478: unparsed entity, in the value of an <kw>ENTITY</kw> or <kw>ENTITIES</kw>
! 2479: attribute.
! 2480: If the same entity is declared more than once, the first declaration
! 2481: encountered is binding; at user option, an XML processor may issue a
! 2482: warning if entities are declared multiple times.</termdef>
! 2483: </p>
! 2484:
! 2485: <div3 id="sec-internal-ent">
! 2486: <head>Internal Entities</head>
! 2487:
! 2488: <p><termdef id="dt-internent" term="Internal Entity Replacement Text">If
! 2489: the entity definition is an
! 2490: <nt def="NT-EntityValue">EntityValue</nt>,
! 2491: the defined entity is called an <term>internal entity</term>.
! 2492: There is no separate physical
! 2493: storage object, and the content of the entity is given in the
! 2494: declaration. </termdef>
! 2495: Note that some processing of entity and character references in the
! 2496: <termref def="dt-litentval">literal entity value</termref> may be required to
! 2497: produce the correct <termref def="dt-repltext">replacement
! 2498: text</termref>: see <specref ref="intern-replacement"/>.
! 2499: </p>
! 2500: <p>An internal entity is a <termref def="dt-parsedent">parsed
! 2501: entity</termref>.</p>
! 2502: <p>Example of an internal entity declaration:
! 2503: <eg><!ENTITY Pub-Status "This is a pre-release of the
! 2504: specification."></eg></p>
! 2505: </div3>
! 2506:
! 2507: <div3 id="sec-external-ent">
! 2508: <head>External Entities</head>
! 2509:
! 2510: <p><termdef id="dt-extent" term="External Entity">If the entity is not
! 2511: internal, it is an <term>external
! 2512: entity</term>, declared as follows:
! 2513: <scrap lang="ebnf">
! 2514: <head>External Entity Declaration</head>
! 2515: <!--
! 2516: <prod id='NT-ExternalDef'><lhs>ExternalDef</lhs>
! 2517: <rhs></prod> -->
! 2518: <prod id="NT-ExternalID"><lhs>ExternalID</lhs>
! 2519: <rhs>'SYSTEM' <nt def="NT-S">S</nt>
! 2520: <nt def="NT-SystemLiteral">SystemLiteral</nt></rhs>
! 2521: <rhs>| 'PUBLIC' <nt def="NT-S">S</nt>
! 2522: <nt def="NT-PubidLiteral">PubidLiteral</nt>
! 2523: <nt def="NT-S">S</nt>
! 2524: <nt def="NT-SystemLiteral">SystemLiteral</nt>
! 2525: </rhs>
! 2526: </prod>
! 2527: <prod id="NT-NDataDecl"><lhs>NDataDecl</lhs>
! 2528: <rhs><nt def="NT-S">S</nt> 'NDATA' <nt def="NT-S">S</nt>
! 2529: <nt def="NT-Name">Name</nt></rhs>
! 2530: <vc def="not-declared"/></prod>
! 2531: </scrap>
! 2532: If the <nt def="NT-NDataDecl">NDataDecl</nt> is present, this is a
! 2533: general <termref def="dt-unparsed">unparsed
! 2534: entity</termref>; otherwise it is a parsed entity.</termdef></p>
! 2535: <vcnote id="not-declared">
! 2536: <head>Notation Declared</head>
! 2537: <p>
! 2538: The <nt def="NT-Name">Name</nt> must match the declared name of a
! 2539: <termref def="dt-notation">notation</termref>.
! 2540: </p>
! 2541: </vcnote>
! 2542: <p><termdef id="dt-sysid" term="System Identifier">The
! 2543: <nt def="NT-SystemLiteral">SystemLiteral</nt>
! 2544: is called the entity's <term>system identifier</term>. It is a URI,
! 2545: which may be used to retrieve the entity.</termdef>
! 2546: Note that the hash mark (<code>#</code>) and fragment identifier
! 2547: frequently used with URIs are not, formally, part of the URI itself;
! 2548: an XML processor may signal an error if a fragment identifier is
! 2549: given as part of a system identifier.
! 2550: Unless otherwise provided by information outside the scope of this
! 2551: specification (e.g. a special XML element type defined by a particular
! 2552: DTD, or a processing instruction defined by a particular application
! 2553: specification), relative URIs are relative to the location of the
! 2554: resource within which the entity declaration occurs.
! 2555: A URI might thus be relative to the
! 2556: <termref def="dt-docent">document entity</termref>, to the entity
! 2557: containing the <termref def="dt-doctype">external DTD subset</termref>,
! 2558: or to some other <termref def="dt-extent">external parameter entity</termref>.
! 2559: </p>
! 2560: <p>An XML processor should handle a non-ASCII character in a URI by
! 2561: representing the character in UTF-8 as one or more bytes, and then
! 2562: escaping these bytes with the URI escaping mechanism (i.e., by
! 2563: converting each byte to %HH, where HH is the hexadecimal notation of the
! 2564: byte value).</p>
! 2565: <p><termdef id="dt-pubid" term="Public identifier">
! 2566: In addition to a system identifier, an external identifier may
! 2567: include a <term>public identifier</term>.</termdef>
! 2568: An XML processor attempting to retrieve the entity's content may use the public
! 2569: identifier to try to generate an alternative URI. If the processor
! 2570: is unable to do so, it must use the URI specified in the system
! 2571: literal. Before a match is attempted, all strings
! 2572: of white space in the public identifier must be normalized to single space characters (#x20),
! 2573: and leading and trailing white space must be removed.</p>
! 2574: <p>Examples of external entity declarations:
! 2575: <eg><!ENTITY open-hatch
! 2576: SYSTEM "http://www.textuality.com/boilerplate/OpenHatch.xml">
! 2577: <!ENTITY open-hatch
! 2578: PUBLIC "-//Textuality//TEXT Standard open-hatch boilerplate//EN"
! 2579: "http://www.textuality.com/boilerplate/OpenHatch.xml">
! 2580: <!ENTITY hatch-pic
! 2581: SYSTEM "../grafix/OpenHatch.gif"
! 2582: NDATA gif ></eg></p>
! 2583: </div3>
! 2584:
! 2585: </div2>
! 2586:
! 2587: <div2 id="TextEntities">
! 2588: <head>Parsed Entities</head>
! 2589: <div3 id="sec-TextDecl">
! 2590: <head>The Text Declaration</head>
! 2591: <p>External parsed entities may each begin with a <term>text
! 2592: declaration</term>.
! 2593: <scrap lang="ebnf">
! 2594: <head>Text Declaration</head>
! 2595: <prodgroup pcw4="12.5" pcw5="13">
! 2596: <prod id="NT-TextDecl"><lhs>TextDecl</lhs>
! 2597: <rhs>&xmlpio;
! 2598: <nt def="NT-VersionInfo">VersionInfo</nt>?
! 2599: <nt def="NT-EncodingDecl">EncodingDecl</nt>
! 2600: <nt def="NT-S">S</nt>? &pic;</rhs>
! 2601: </prod>
! 2602: </prodgroup>
! 2603: </scrap>
! 2604: </p>
! 2605: <p>The text declaration must be provided literally, not
! 2606: by reference to a parsed entity.
! 2607: No text declaration may appear at any position other than the beginning of
! 2608: an external parsed entity.</p>
! 2609: </div3>
! 2610: <div3 id="wf-entities">
! 2611: <head>Well-Formed Parsed Entities</head>
! 2612: <p>The document entity is well-formed if it matches the production labeled
! 2613: <nt def="NT-document">document</nt>.
! 2614: An external general
! 2615: parsed entity is well-formed if it matches the production labeled
! 2616: <nt def="NT-extParsedEnt">extParsedEnt</nt>.
! 2617: An external parameter
! 2618: entity is well-formed if it matches the production labeled
! 2619: <nt def="NT-extPE">extPE</nt>.
! 2620: <scrap lang="ebnf">
! 2621: <head>Well-Formed External Parsed Entity</head>
! 2622: <prod id="NT-extParsedEnt"><lhs>extParsedEnt</lhs>
! 2623: <rhs><nt def="NT-TextDecl">TextDecl</nt>?
! 2624: <nt def="NT-content">content</nt></rhs>
! 2625: </prod>
! 2626: <prod id="NT-extPE"><lhs>extPE</lhs>
! 2627: <rhs><nt def="NT-TextDecl">TextDecl</nt>?
! 2628: <nt def="NT-extSubsetDecl">extSubsetDecl</nt></rhs>
! 2629: </prod>
! 2630: </scrap>
! 2631: An internal general parsed entity is well-formed if its replacement text
! 2632: matches the production labeled
! 2633: <nt def="NT-content">content</nt>.
! 2634: All internal parameter entities are well-formed by definition.
! 2635: </p>
! 2636: <p>A consequence of well-formedness in entities is that the logical
! 2637: and physical structures in an XML document are properly nested; no
! 2638: <termref def="dt-stag">start-tag</termref>,
! 2639: <termref def="dt-etag">end-tag</termref>,
! 2640: <termref def="dt-empty">empty-element tag</termref>,
! 2641: <termref def="dt-element">element</termref>,
! 2642: <termref def="dt-comment">comment</termref>,
! 2643: <termref def="dt-pi">processing instruction</termref>,
! 2644: <termref def="dt-charref">character
! 2645: reference</termref>, or
! 2646: <termref def="dt-entref">entity reference</termref>
! 2647: can begin in one entity and end in another.</p>
! 2648: </div3>
! 2649: <div3 id="charencoding">
! 2650: <head>Character Encoding in Entities</head>
! 2651:
! 2652: <p>Each external parsed entity in an XML document may use a different
! 2653: encoding for its characters. All XML processors must be able to read
! 2654: entities in either UTF-8 or UTF-16.
! 2655:
! 2656: </p>
! 2657: <p>Entities encoded in UTF-16 must
! 2658: begin with the Byte Order Mark described by ISO/IEC 10646 Annex E and
! 2659: Unicode Appendix B (the ZERO WIDTH NO-BREAK SPACE character, #xFEFF).
! 2660: This is an encoding signature, not part of either the markup or the
! 2661: character data of the XML document.
! 2662: XML processors must be able to use this character to
! 2663: differentiate between UTF-8 and UTF-16 encoded documents.</p>
! 2664: <p>Although an XML processor is required to read only entities in
! 2665: the UTF-8 and UTF-16 encodings, it is recognized that other encodings are
! 2666: used around the world, and it may be desired for XML processors
! 2667: to read entities that use them.
! 2668: Parsed entities which are stored in an encoding other than
! 2669: UTF-8 or UTF-16 must begin with a <titleref href="TextDecl">text
! 2670: declaration</titleref> containing an encoding declaration:
! 2671: <scrap lang="ebnf">
! 2672: <head>Encoding Declaration</head>
! 2673: <prod id="NT-EncodingDecl"><lhs>EncodingDecl</lhs>
! 2674: <rhs><nt def="NT-S">S</nt>
! 2675: 'encoding' <nt def="NT-Eq">Eq</nt>
! 2676: ('"' <nt def="NT-EncName">EncName</nt> '"' |
! 2677: "'" <nt def="NT-EncName">EncName</nt> "'" )
! 2678: </rhs>
! 2679: </prod>
! 2680: <prod id="NT-EncName"><lhs>EncName</lhs>
! 2681: <rhs>[A-Za-z] ([A-Za-z0-9._] | '-')*</rhs>
! 2682: <com>Encoding name contains only Latin characters</com>
! 2683: </prod>
! 2684: </scrap>
! 2685: In the <termref def="dt-docent">document entity</termref>, the encoding
! 2686: declaration is part of the <termref def="dt-xmldecl">XML declaration</termref>.
! 2687: The <nt def="NT-EncName">EncName</nt> is the name of the encoding used.
! 2688: </p>
! 2689: <!-- FINAL EDIT: check name of IANA and charset names -->
! 2690: <p>In an encoding declaration, the values
! 2691: "<code>UTF-8</code>",
! 2692: "<code>UTF-16</code>",
! 2693: "<code>ISO-10646-UCS-2</code>", and
! 2694: "<code>ISO-10646-UCS-4</code>" should be
! 2695: used for the various encodings and transformations of Unicode /
! 2696: ISO/IEC 10646, the values
! 2697: "<code>ISO-8859-1</code>",
! 2698: "<code>ISO-8859-2</code>", ...
! 2699: "<code>ISO-8859-9</code>" should be used for the parts of ISO 8859, and
! 2700: the values
! 2701: "<code>ISO-2022-JP</code>",
! 2702: "<code>Shift_JIS</code>", and
! 2703: "<code>EUC-JP</code>"
! 2704: should be used for the various encoded forms of JIS X-0208-1997. XML
! 2705: processors may recognize other encodings; it is recommended that
! 2706: character encodings registered (as <emph>charset</emph>s)
! 2707: with the Internet Assigned Numbers
! 2708: Authority <bibref ref="IANA"/>, other than those just listed, should be
! 2709: referred to
! 2710: using their registered names.
! 2711: Note that these registered names are defined to be
! 2712: case-insensitive, so processors wishing to match against them
! 2713: should do so in a case-insensitive
! 2714: way.</p>
! 2715: <p>In the absence of information provided by an external
! 2716: transport protocol (e.g. HTTP or MIME),
! 2717: it is an <termref def="dt-error">error</termref> for an entity including
! 2718: an encoding declaration to be presented to the XML processor
! 2719: in an encoding other than that named in the declaration,
! 2720: for an encoding declaration to occur other than at the beginning
! 2721: of an external entity, or for
! 2722: an entity which begins with neither a Byte Order Mark nor an encoding
! 2723: declaration to use an encoding other than UTF-8.
! 2724: Note that since ASCII
! 2725: is a subset of UTF-8, ordinary ASCII entities do not strictly need
! 2726: an encoding declaration.</p>
! 2727:
! 2728: <p>It is a <termref def="dt-fatal">fatal error</termref> when an XML processor
! 2729: encounters an entity with an encoding that it is unable to process.</p>
! 2730: <p>Examples of encoding declarations:
! 2731: <eg><?xml encoding='UTF-8'?>
! 2732: <?xml encoding='EUC-JP'?></eg></p>
! 2733: </div3>
! 2734: </div2>
! 2735: <div2 id="entproc">
! 2736: <head>XML Processor Treatment of Entities and References</head>
! 2737: <p>The table below summarizes the contexts in which character references,
! 2738: entity references, and invocations of unparsed entities might appear and the
! 2739: required behavior of an <termref def="dt-xml-proc">XML processor</termref> in
! 2740: each case.
! 2741: The labels in the leftmost column describe the recognition context:
! 2742: <glist>
! 2743: <gitem><label>Reference in Content</label>
! 2744: <def><p>as a reference
! 2745: anywhere after the <termref def="dt-stag">start-tag</termref> and
! 2746: before the <termref def="dt-etag">end-tag</termref> of an element; corresponds
! 2747: to the nonterminal <nt def="NT-content">content</nt>.</p></def>
! 2748: </gitem>
! 2749: <gitem>
! 2750: <label>Reference in Attribute Value</label>
! 2751: <def><p>as a reference within either the value of an attribute in a
! 2752: <termref def="dt-stag">start-tag</termref>, or a default
! 2753: value in an <termref def="dt-attdecl">attribute declaration</termref>;
! 2754: corresponds to the nonterminal
! 2755: <nt def="NT-AttValue">AttValue</nt>.</p></def></gitem>
! 2756: <gitem>
! 2757: <label>Occurs as Attribute Value</label>
! 2758: <def><p>as a <nt def="NT-Name">Name</nt>, not a reference, appearing either as
! 2759: the value of an
! 2760: attribute which has been declared as type <kw>ENTITY</kw>, or as one of
! 2761: the space-separated tokens in the value of an attribute which has been
! 2762: declared as type <kw>ENTITIES</kw>.</p>
! 2763: </def></gitem>
! 2764: <gitem><label>Reference in Entity Value</label>
! 2765: <def><p>as a reference
! 2766: within a parameter or internal entity's
! 2767: <termref def="dt-litentval">literal entity value</termref> in
! 2768: the entity's declaration; corresponds to the nonterminal
! 2769: <nt def="NT-EntityValue">EntityValue</nt>.</p></def></gitem>
! 2770: <gitem><label>Reference in DTD</label>
! 2771: <def><p>as a reference within either the internal or external subsets of the
! 2772: <termref def="dt-doctype">DTD</termref>, but outside
! 2773: of an <nt def="NT-EntityValue">EntityValue</nt> or
! 2774: <nt def="NT-AttValue">AttValue</nt>.</p></def>
! 2775: </gitem>
! 2776: </glist></p>
! 2777: <htable border="1" cellpadding="7" align="center">
! 2778: <htbody>
! 2779: <tr><td bgcolor="&cellback;" rowspan="2" colspan="1"/>
! 2780: <td bgcolor="&cellback;" align="center" valign="bottom" colspan="4">Entity Type</td>
! 2781: <td bgcolor="&cellback;" rowspan="2" align="center">Character</td>
! 2782: </tr>
! 2783: <tr align="center" valign="bottom">
! 2784: <td bgcolor="&cellback;">Parameter</td>
! 2785: <td bgcolor="&cellback;">Internal
! 2786: General</td>
! 2787: <td bgcolor="&cellback;">External Parsed
! 2788: General</td>
! 2789: <td bgcolor="&cellback;">Unparsed</td>
! 2790: </tr>
! 2791: <tr align="center" valign="middle">
! 2792:
! 2793: <td bgcolor="&cellback;" align="right">Reference
! 2794: in Content</td>
! 2795: <td bgcolor="&cellback;"><titleref href="not-recognized">Not recognized</titleref></td>
! 2796: <td bgcolor="&cellback;"><titleref href="included">Included</titleref></td>
! 2797: <td bgcolor="&cellback;"><titleref href="include-if-valid">Included if validating</titleref></td>
! 2798: <td bgcolor="&cellback;"><titleref href="forbidden">Forbidden</titleref></td>
! 2799: <td bgcolor="&cellback;"><titleref href="included">Included</titleref></td>
! 2800: </tr>
! 2801: <tr align="center" valign="middle">
! 2802: <td bgcolor="&cellback;" align="right">Reference
! 2803: in Attribute Value</td>
! 2804: <td bgcolor="&cellback;"><titleref href="not-recognized">Not recognized</titleref></td>
! 2805: <td bgcolor="&cellback;"><titleref href="inliteral">Included in literal</titleref></td>
! 2806: <td bgcolor="&cellback;"><titleref href="forbidden">Forbidden</titleref></td>
! 2807: <td bgcolor="&cellback;"><titleref href="forbidden">Forbidden</titleref></td>
! 2808: <td bgcolor="&cellback;"><titleref href="included">Included</titleref></td>
! 2809: </tr>
! 2810: <tr align="center" valign="middle">
! 2811: <td bgcolor="&cellback;" align="right">Occurs as
! 2812: Attribute Value</td>
! 2813: <td bgcolor="&cellback;"><titleref href="not-recognized">Not recognized</titleref></td>
! 2814: <td bgcolor="&cellback;"><titleref href="not-recognized">Forbidden</titleref></td>
! 2815: <td bgcolor="&cellback;"><titleref href="not-recognized">Forbidden</titleref></td>
! 2816: <td bgcolor="&cellback;"><titleref href="notify">Notify</titleref></td>
! 2817: <td bgcolor="&cellback;"><titleref href="not recognized">Not recognized</titleref></td>
! 2818: </tr>
! 2819: <tr align="center" valign="middle">
! 2820: <td bgcolor="&cellback;" align="right">Reference
! 2821: in EntityValue</td>
! 2822: <td bgcolor="&cellback;"><titleref href="inliteral">Included in literal</titleref></td>
! 2823: <td bgcolor="&cellback;"><titleref href="bypass">Bypassed</titleref></td>
! 2824: <td bgcolor="&cellback;"><titleref href="bypass">Bypassed</titleref></td>
! 2825: <td bgcolor="&cellback;"><titleref href="forbidden">Forbidden</titleref></td>
! 2826: <td bgcolor="&cellback;"><titleref href="included">Included</titleref></td>
! 2827: </tr>
! 2828: <tr align="center" valign="middle">
! 2829: <td bgcolor="&cellback;" align="right">Reference
! 2830: in DTD</td>
! 2831: <td bgcolor="&cellback;"><titleref href="as-PE">Included as PE</titleref></td>
! 2832: <td bgcolor="&cellback;"><titleref href="forbidden">Forbidden</titleref></td>
! 2833: <td bgcolor="&cellback;"><titleref href="forbidden">Forbidden</titleref></td>
! 2834: <td bgcolor="&cellback;"><titleref href="forbidden">Forbidden</titleref></td>
! 2835: <td bgcolor="&cellback;"><titleref href="forbidden">Forbidden</titleref></td>
! 2836: </tr>
! 2837: </htbody>
! 2838: </htable>
! 2839: <div3 id="not-recognized">
! 2840: <head>Not Recognized</head>
! 2841: <p>Outside the DTD, the <code>%</code> character has no
! 2842: special significance; thus, what would be parameter entity references in the
! 2843: DTD are not recognized as markup in <nt def="NT-content">content</nt>.
! 2844: Similarly, the names of unparsed entities are not recognized except
! 2845: when they appear in the value of an appropriately declared attribute.
! 2846: </p>
! 2847: </div3>
! 2848: <div3 id="included">
! 2849: <head>Included</head>
! 2850: <p><termdef id="dt-include" term="Include">An entity is
! 2851: <term>included</term> when its
! 2852: <termref def="dt-repltext">replacement text</termref> is retrieved
! 2853: and processed, in place of the reference itself,
! 2854: as though it were part of the document at the location the
! 2855: reference was recognized.
! 2856: The replacement text may contain both
! 2857: <termref def="dt-chardata">character data</termref>
! 2858: and (except for parameter entities) <termref def="dt-markup">markup</termref>,
! 2859: which must be recognized in
! 2860: the usual way, except that the replacement text of entities used to escape
! 2861: markup delimiters (the entities &magicents;) is always treated as
! 2862: data. (The string "<code>AT&amp;T;</code>" expands to
! 2863: "<code>AT&T;</code>" and the remaining ampersand is not recognized
! 2864: as an entity-reference delimiter.)
! 2865: A character reference is <term>included</term> when the indicated
! 2866: character is processed in place of the reference itself.
! 2867: </termdef></p>
! 2868: </div3>
! 2869: <div3 id="include-if-valid">
! 2870: <head>Included If Validating</head>
! 2871: <p>When an XML processor recognizes a reference to a parsed entity, in order
! 2872: to <termref def="dt-valid">validate</termref>
! 2873: the document, the processor must
! 2874: <termref def="dt-include">include</termref> its
! 2875: replacement text.
! 2876: If the entity is external, and the processor is not
! 2877: attempting to validate the XML document, the
! 2878: processor <termref def="dt-may">may</termref>, but need not,
! 2879: include the entity's replacement text.
! 2880: If a non-validating parser does not include the replacement text,
! 2881: it must inform the application that it recognized, but did not
! 2882: read, the entity.</p>
! 2883: <p>This rule is based on the recognition that the automatic inclusion
! 2884: provided by the SGML and XML entity mechanism, primarily designed
! 2885: to support modularity in authoring, is not necessarily
! 2886: appropriate for other applications, in particular document browsing.
! 2887: Browsers, for example, when encountering an external parsed entity reference,
! 2888: might choose to provide a visual indication of the entity's
! 2889: presence and retrieve it for display only on demand.
! 2890: </p>
! 2891: </div3>
! 2892: <div3 id="forbidden">
! 2893: <head>Forbidden</head>
! 2894: <p>The following are forbidden, and constitute
! 2895: <termref def="dt-fatal">fatal</termref> errors:
! 2896: <ulist>
! 2897: <item><p>the appearance of a reference to an
! 2898: <termref def="dt-unparsed">unparsed entity</termref>.
! 2899: </p></item>
! 2900: <item><p>the appearance of any character or general-entity reference in the
! 2901: DTD except within an <nt def="NT-EntityValue">EntityValue</nt> or
! 2902: <nt def="NT-AttValue">AttValue</nt>.</p></item>
! 2903: <item><p>a reference to an external entity in an attribute value.</p>
! 2904: </item>
! 2905: </ulist>
! 2906: </p>
! 2907: </div3>
! 2908: <div3 id="inliteral">
! 2909: <head>Included in Literal</head>
! 2910: <p>When an <termref def="dt-entref">entity reference</termref> appears in an
! 2911: attribute value, or a parameter entity reference appears in a literal entity
! 2912: value, its <termref def="dt-repltext">replacement text</termref> is
! 2913: processed in place of the reference itself as though it
! 2914: were part of the document at the location the reference was recognized,
! 2915: except that a single or double quote character in the replacement text
! 2916: is always treated as a normal data character and will not terminate the
! 2917: literal.
! 2918: For example, this is well-formed:
! 2919: <eg><![CDATA[<!ENTITY % YN '"Yes"' >
! 2920: <!ENTITY WhatHeSaid "He said &YN;" >]]></eg>
! 2921: while this is not:
! 2922: <eg><!ENTITY EndAttr "27'" >
! 2923: <element attribute='a-&EndAttr;></eg>
! 2924: </p></div3>
! 2925: <div3 id="notify">
! 2926: <head>Notify</head>
! 2927: <p>When the name of an <termref def="dt-unparsed">unparsed
! 2928: entity</termref> appears as a token in the
! 2929: value of an attribute of declared type <kw>ENTITY</kw> or <kw>ENTITIES</kw>,
! 2930: a validating processor must inform the
! 2931: application of the <termref def="dt-sysid">system</termref>
! 2932: and <termref def="dt-pubid">public</termref> (if any)
! 2933: identifiers for both the entity and its associated
! 2934: <termref def="dt-notation">notation</termref>.</p>
! 2935: </div3>
! 2936: <div3 id="bypass">
! 2937: <head>Bypassed</head>
! 2938: <p>When a general entity reference appears in the
! 2939: <nt def="NT-EntityValue">EntityValue</nt> in an entity declaration,
! 2940: it is bypassed and left as is.</p>
! 2941: </div3>
! 2942: <div3 id="as-PE">
! 2943: <head>Included as PE</head>
! 2944: <p>Just as with external parsed entities, parameter entities
! 2945: need only be <titleref href="include-if-valid">included if
! 2946: validating</titleref>.
! 2947: When a parameter-entity reference is recognized in the DTD
! 2948: and included, its
! 2949: <termref def="dt-repltext">replacement
! 2950: text</termref> is enlarged by the attachment of one leading and one following
! 2951: space (#x20) character; the intent is to constrain the replacement
! 2952: text of parameter
! 2953: entities to contain an integral number of grammatical tokens in the DTD.
! 2954: </p>
! 2955: </div3>
! 2956:
! 2957: </div2>
! 2958: <div2 id="intern-replacement">
! 2959: <head>Construction of Internal Entity Replacement Text</head>
! 2960: <p>In discussing the treatment
! 2961: of internal entities, it is
! 2962: useful to distinguish two forms of the entity's value.
! 2963: <termdef id="dt-litentval" term="Literal Entity Value">The <term>literal
! 2964: entity value</term> is the quoted string actually
! 2965: present in the entity declaration, corresponding to the
! 2966: non-terminal <nt def="NT-EntityValue">EntityValue</nt>.</termdef>
! 2967: <termdef id="dt-repltext" term="Replacement Text">The <term>replacement
! 2968: text</term> is the content of the entity, after
! 2969: replacement of character references and parameter-entity
! 2970: references.
! 2971: </termdef></p>
! 2972:
! 2973: <p>The literal entity value
! 2974: as given in an internal entity declaration
! 2975: (<nt def="NT-EntityValue">EntityValue</nt>) may contain character,
! 2976: parameter-entity, and general-entity references.
! 2977: Such references must be contained entirely within the
! 2978: literal entity value.
! 2979: The actual replacement text that is
! 2980: <termref def="dt-include">included</termref> as described above
! 2981: must contain the <emph>replacement text</emph> of any
! 2982: parameter entities referred to, and must contain the character
! 2983: referred to, in place of any character references in the
! 2984: literal entity value; however,
! 2985: general-entity references must be left as-is, unexpanded.
! 2986: For example, given the following declarations:
! 2987:
! 2988: <eg><![CDATA[<!ENTITY % pub "Éditions Gallimard" >
! 2989: <!ENTITY rights "All rights reserved" >
! 2990: <!ENTITY book "La Peste: Albert Camus,
! 2991: © 1947 %pub;. &rights;" >]]></eg>
! 2992: then the replacement text for the entity "<code>book</code>" is:
! 2993: <eg>La Peste: Albert Camus,
! 2994: Š 1947 Éditions Gallimard. &rights;</eg>
! 2995: The general-entity reference "<code>&rights;</code>" would be expanded
! 2996: should the reference "<code>&book;</code>" appear in the document's
! 2997: content or an attribute value.</p>
! 2998: <p>These simple rules may have complex interactions; for a detailed
! 2999: discussion of a difficult example, see
! 3000: <specref ref="sec-entexpand"/>.
! 3001: </p>
! 3002:
! 3003: </div2>
! 3004: <div2 id="sec-predefined-ent">
! 3005: <head>Predefined Entities</head>
! 3006: <p><termdef id="dt-escape" term="escape">Entity and character
! 3007: references can both be used to <term>escape</term> the left angle bracket,
! 3008: ampersand, and other delimiters. A set of general entities
! 3009: (&magicents;) is specified for this purpose.
! 3010: Numeric character references may also be used; they are
! 3011: expanded immediately when recognized and must be treated as
! 3012: character data, so the numeric character references
! 3013: "<code>&#60;</code>" and "<code>&#38;</code>" may be used to
! 3014: escape <code><</code> and <code>&</code> when they occur
! 3015: in character data.</termdef></p>
! 3016: <p>All XML processors must recognize these entities whether they
! 3017: are declared or not.
! 3018: <termref def="dt-interop">For interoperability</termref>,
! 3019: valid XML documents should declare these
! 3020: entities, like any others, before using them.
! 3021: If the entities in question are declared, they must be declared
! 3022: as internal entities whose replacement text is the single
! 3023: character being escaped or a character reference to
! 3024: that character, as shown below.
! 3025: <eg><![CDATA[<!ENTITY lt "&#60;">
! 3026: <!ENTITY gt ">">
! 3027: <!ENTITY amp "&#38;">
! 3028: <!ENTITY apos "'">
! 3029: <!ENTITY quot """>
! 3030: ]]></eg>
! 3031: Note that the <code><</code> and <code>&</code> characters
! 3032: in the declarations of "<code>lt</code>" and "<code>amp</code>"
! 3033: are doubly escaped to meet the requirement that entity replacement
! 3034: be well-formed.
! 3035: </p>
! 3036: </div2>
! 3037:
! 3038: <div2 id="Notations">
! 3039: <head>Notation Declarations</head>
! 3040:
! 3041: <p><termdef id="dt-notation" term="Notation"><term>Notations</term> identify by
! 3042: name the format of <termref def="dt-extent">unparsed
! 3043: entities</termref>, the
! 3044: format of elements which bear a notation attribute,
! 3045: or the application to which
! 3046: a <termref def="dt-pi">processing instruction</termref> is
! 3047: addressed.</termdef></p>
! 3048: <p><termdef id="dt-notdecl" term="Notation Declaration">
! 3049: <term>Notation declarations</term>
! 3050: provide a name for the notation, for use in
! 3051: entity and attribute-list declarations and in attribute specifications,
! 3052: and an external identifier for the notation which may allow an XML
! 3053: processor or its client application to locate a helper application
! 3054: capable of processing data in the given notation.
! 3055: <scrap lang="ebnf">
! 3056: <head>Notation Declarations</head>
! 3057: <prod id="NT-NotationDecl"><lhs>NotationDecl</lhs>
! 3058: <rhs>'<!NOTATION' <nt def="NT-S">S</nt> <nt def="NT-Name">Name</nt>
! 3059: <nt def="NT-S">S</nt>
! 3060: (<nt def="NT-ExternalID">ExternalID</nt> |
! 3061: <nt def="NT-PublicID">PublicID</nt>)
! 3062: <nt def="NT-S">S</nt>? '>'</rhs></prod>
! 3063: <prod id="NT-PublicID"><lhs>PublicID</lhs>
! 3064: <rhs>'PUBLIC' <nt def="NT-S">S</nt>
! 3065: <nt def="NT-PubidLiteral">PubidLiteral</nt>
! 3066: </rhs></prod>
! 3067: </scrap>
! 3068: </termdef></p>
! 3069: <p>XML processors must provide applications with the name and external
! 3070: identifier(s) of any notation declared and referred to in an attribute
! 3071: value, attribute definition, or entity declaration. They may
! 3072: additionally resolve the external identifier into the
! 3073: <termref def="dt-sysid">system identifier</termref>,
! 3074: file name, or other information needed to allow the
! 3075: application to call a processor for data in the notation described. (It
! 3076: is not an error, however, for XML documents to declare and refer to
! 3077: notations for which notation-specific applications are not available on
! 3078: the system where the XML processor or application is running.)</p>
! 3079: </div2>
! 3080:
! 3081:
! 3082: <div2 id="sec-doc-entity">
! 3083: <head>Document Entity</head>
! 3084:
! 3085: <p><termdef id="dt-docent" term="Document Entity">The <term>document
! 3086: entity</term> serves as the root of the entity
! 3087: tree and a starting-point for an <termref def="dt-xml-proc">XML
! 3088: processor</termref>.</termdef>
! 3089: This specification does
! 3090: not specify how the document entity is to be located by an XML
! 3091: processor; unlike other entities, the document entity has no name and might
! 3092: well appear on a processor input stream
! 3093: without any identification at all.</p>
! 3094: </div2>
! 3095:
! 3096:
! 3097: </div1>
! 3098: <!-- &Conformance; -->
! 3099:
! 3100: <div1 id="sec-conformance">
! 3101: <head>Conformance</head>
! 3102:
! 3103: <div2 id="proc-types">
! 3104: <head>Validating and Non-Validating Processors</head>
! 3105: <p>Conforming <termref def="dt-xml-proc">XML processors</termref> fall into two
! 3106: classes: validating and non-validating.</p>
! 3107: <p>Validating and non-validating processors alike must report
! 3108: violations of this specification's well-formedness constraints
! 3109: in the content of the
! 3110: <termref def="dt-docent">document entity</termref> and any
! 3111: other <termref def="dt-parsedent">parsed entities</termref> that
! 3112: they read.</p>
! 3113: <p><termdef id="dt-validating" term="Validating Processor">
! 3114: <term>Validating processors</term> must report
! 3115: violations of the constraints expressed by the declarations in the
! 3116: <termref def="dt-doctype">DTD</termref>, and
! 3117: failures to fulfill the validity constraints given
! 3118: in this specification.
! 3119: </termdef>
! 3120: To accomplish this, validating XML processors must read and process the entire
! 3121: DTD and all external parsed entities referenced in the document.
! 3122: </p>
! 3123: <p>Non-validating processors are required to check only the
! 3124: <termref def="dt-docent">document entity</termref>, including
! 3125: the entire internal DTD subset, for well-formedness.
! 3126: <termdef id="dt-use-mdecl" term="Process Declarations">
! 3127: While they are not required to check the document for validity,
! 3128: they are required to
! 3129: <term>process</term> all the declarations they read in the
! 3130: internal DTD subset and in any parameter entity that they
! 3131: read, up to the first reference
! 3132: to a parameter entity that they do <emph>not</emph> read; that is to
! 3133: say, they must
! 3134: use the information in those declarations to
! 3135: <titleref href="AVNormalize">normalize</titleref> attribute values,
! 3136: <titleref href="included">include</titleref> the replacement text of
! 3137: internal entities, and supply
! 3138: <titleref href="sec-attr-defaults">default attribute values</titleref>.
! 3139: </termdef>
! 3140: They must not <termref def="dt-use-mdecl">process</termref>
! 3141: <termref def="dt-entdecl">entity declarations</termref> or
! 3142: <termref def="dt-attdecl">attribute-list declarations</termref>
! 3143: encountered after a reference to a parameter entity that is not
! 3144: read, since the entity may have contained overriding declarations.
! 3145: </p>
! 3146: </div2>
! 3147: <div2 id="safe-behavior">
! 3148: <head>Using XML Processors</head>
! 3149: <p>The behavior of a validating XML processor is highly predictable; it
! 3150: must read every piece of a document and report all well-formedness and
! 3151: validity violations.
! 3152: Less is required of a non-validating processor; it need not read any
! 3153: part of the document other than the document entity.
! 3154: This has two effects that may be important to users of XML processors:
! 3155: <ulist>
! 3156: <item><p>Certain well-formedness errors, specifically those that require
! 3157: reading external entities, may not be detected by a non-validating processor.
! 3158: Examples include the constraints entitled
! 3159: <titleref href="wf-entdeclared">Entity Declared</titleref>,
! 3160: <titleref href="wf-textent">Parsed Entity</titleref>, and
! 3161: <titleref href="wf-norecursion">No Recursion</titleref>, as well
! 3162: as some of the cases described as
! 3163: <titleref href="forbidden">forbidden</titleref> in
! 3164: <specref ref="entproc"/>.</p></item>
! 3165: <item><p>The information passed from the processor to the application may
! 3166: vary, depending on whether the processor reads
! 3167: parameter and external entities.
! 3168: For example, a non-validating processor may not
! 3169: <titleref href="AVNormalize">normalize</titleref> attribute values,
! 3170: <titleref href="included">include</titleref> the replacement text of
! 3171: internal entities, or supply
! 3172: <titleref href="sec-attr-defaults">default attribute values</titleref>,
! 3173: where doing so depends on having read declarations in
! 3174: external or parameter entities.</p></item>
! 3175: </ulist>
! 3176: </p>
! 3177: <p>For maximum reliability in interoperating between different XML
! 3178: processors, applications which use non-validating processors should not
! 3179: rely on any behaviors not required of such processors.
! 3180: Applications which require facilities such as the use of default
! 3181: attributes or internal entities which are declared in external
! 3182: entities should use validating XML processors.</p>
! 3183: </div2>
! 3184: </div1>
! 3185:
! 3186: <div1 id="sec-notation">
! 3187: <head>Notation</head>
! 3188:
! 3189: <p>The formal grammar of XML is given in this specification using a simple
! 3190: Extended Backus-Naur Form (EBNF) notation. Each rule in the grammar defines
! 3191: one symbol, in the form
! 3192: <eg>symbol ::= expression</eg></p>
! 3193: <p>Symbols are written with an initial capital letter if they are
! 3194: defined by a regular expression, or with an initial lower case letter
! 3195: otherwise.
! 3196: Literal strings are quoted.
! 3197:
! 3198: </p>
! 3199:
! 3200: <p>Within the expression on the right-hand side of a rule, the following
! 3201: expressions are used to match strings of one or more characters:
! 3202: <glist>
! 3203: <gitem>
! 3204: <label><code>#xN</code></label>
! 3205: <def><p>where <code>N</code> is a hexadecimal integer, the
! 3206: expression matches the character in ISO/IEC 10646 whose canonical
! 3207: (UCS-4)
! 3208: code value, when interpreted as an unsigned binary number, has
! 3209: the value indicated. The number of leading zeros in the
! 3210: <code>#xN</code> form is insignificant; the number of leading
! 3211: zeros in the corresponding code value
! 3212: is governed by the character
! 3213: encoding in use and is not significant for XML.</p></def>
! 3214: </gitem>
! 3215: <gitem>
! 3216: <label><code>[a-zA-Z]</code>, <code>[#xN-#xN]</code></label>
! 3217: <def><p>matches any <termref def="dt-character">character</termref>
! 3218: with a value in the range(s) indicated (inclusive).</p></def>
! 3219: </gitem>
! 3220: <gitem>
! 3221: <label><code>[^a-z]</code>, <code>[^#xN-#xN]</code></label>
! 3222: <def><p>matches any <termref def="dt-character">character</termref>
! 3223: with a value <emph>outside</emph> the
! 3224: range indicated.</p></def>
! 3225: </gitem>
! 3226: <gitem>
! 3227: <label><code>[^abc]</code>, <code>[^#xN#xN#xN]</code></label>
! 3228: <def><p>matches any <termref def="dt-character">character</termref>
! 3229: with a value not among the characters given.</p></def>
! 3230: </gitem>
! 3231: <gitem>
! 3232: <label><code>"string"</code></label>
! 3233: <def><p>matches a literal string <termref def="dt-match">matching</termref>
! 3234: that given inside the double quotes.</p></def>
! 3235: </gitem>
! 3236: <gitem>
! 3237: <label><code>'string'</code></label>
! 3238: <def><p>matches a literal string <termref def="dt-match">matching</termref>
! 3239: that given inside the single quotes.</p></def>
! 3240: </gitem>
! 3241: </glist>
! 3242: These symbols may be combined to match more complex patterns as follows,
! 3243: where <code>A</code> and <code>B</code> represent simple expressions:
! 3244: <glist>
! 3245: <gitem>
! 3246: <label>(<code>expression</code>)</label>
! 3247: <def><p><code>expression</code> is treated as a unit
! 3248: and may be combined as described in this list.</p></def>
! 3249: </gitem>
! 3250: <gitem>
! 3251: <label><code>A?</code></label>
! 3252: <def><p>matches <code>A</code> or nothing; optional <code>A</code>.</p></def>
! 3253: </gitem>
! 3254: <gitem>
! 3255: <label><code>A B</code></label>
! 3256: <def><p>matches <code>A</code> followed by <code>B</code>.</p></def>
! 3257: </gitem>
! 3258: <gitem>
! 3259: <label><code>A | B</code></label>
! 3260: <def><p>matches <code>A</code> or <code>B</code> but not both.</p></def>
! 3261: </gitem>
! 3262: <gitem>
! 3263: <label><code>A - B</code></label>
! 3264: <def><p>matches any string that matches <code>A</code> but does not match
! 3265: <code>B</code>.
! 3266: </p></def>
! 3267: </gitem>
! 3268: <gitem>
! 3269: <label><code>A+</code></label>
! 3270: <def><p>matches one or more occurrences of <code>A</code>.</p></def>
! 3271: </gitem>
! 3272: <gitem>
! 3273: <label><code>A*</code></label>
! 3274: <def><p>matches zero or more occurrences of <code>A</code>.</p></def>
! 3275: </gitem>
! 3276:
! 3277: </glist>
! 3278: Other notations used in the productions are:
! 3279: <glist>
! 3280: <gitem>
! 3281: <label><code>/* ... */</code></label>
! 3282: <def><p>comment.</p></def>
! 3283: </gitem>
! 3284: <gitem>
! 3285: <label><code>[ wfc: ... ]</code></label>
! 3286: <def><p>well-formedness constraint; this identifies by name a
! 3287: constraint on
! 3288: <termref def="dt-wellformed">well-formed</termref> documents
! 3289: associated with a production.</p></def>
! 3290: </gitem>
! 3291: <gitem>
! 3292: <label><code>[ vc: ... ]</code></label>
! 3293: <def><p>validity constraint; this identifies by name a constraint on
! 3294: <termref def="dt-valid">valid</termref> documents associated with
! 3295: a production.</p></def>
! 3296: </gitem>
! 3297: </glist>
! 3298: </p></div1>
! 3299:
! 3300: </body>
! 3301: <back>
! 3302: <!-- &SGML; -->
! 3303:
! 3304:
! 3305: <!-- &Biblio; -->
! 3306: <div1 id="sec-bibliography">
! 3307:
! 3308: <head>References</head>
! 3309: <div2 id="sec-existing-stds">
! 3310: <head>Normative References</head>
! 3311:
! 3312: <blist>
! 3313: <bibl id="IANA" key="IANA">
! 3314: (Internet Assigned Numbers Authority) <emph>Official Names for
! 3315: Character Sets</emph>,
! 3316: ed. Keld Simonsen et al.
! 3317: See <loc href="ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets">ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets</loc>.
! 3318: </bibl>
! 3319:
! 3320: <bibl id="RFC1766" key="IETF RFC 1766">
! 3321: IETF (Internet Engineering Task Force).
! 3322: <emph>RFC 1766: Tags for the Identification of Languages</emph>,
! 3323: ed. H. Alvestrand.
! 3324: 1995.
! 3325: </bibl>
! 3326:
! 3327: <bibl id="ISO639" key="ISO 639">
! 3328: (International Organization for Standardization).
! 3329: <emph>ISO 639:1988 (E).
! 3330: Code for the representation of names of languages.</emph>
! 3331: [Geneva]: International Organization for
! 3332: Standardization, 1988.</bibl>
! 3333:
! 3334: <bibl id="ISO3166" key="ISO 3166">
! 3335: (International Organization for Standardization).
! 3336: <emph>ISO 3166-1:1997 (E).
! 3337: Codes for the representation of names of countries and their subdivisions
! 3338: — Part 1: Country codes</emph>
! 3339: [Geneva]: International Organization for
! 3340: Standardization, 1997.</bibl>
! 3341:
! 3342: <bibl id="ISO10646" key="ISO/IEC 10646">ISO
! 3343: (International Organization for Standardization).
! 3344: <emph>ISO/IEC 10646-1993 (E). Information technology — Universal
! 3345: Multiple-Octet Coded Character Set (UCS) — Part 1:
! 3346: Architecture and Basic Multilingual Plane.</emph>
! 3347: [Geneva]: International Organization for
! 3348: Standardization, 1993 (plus amendments AM 1 through AM 7).
! 3349: </bibl>
! 3350:
! 3351: <bibl id="Unicode" key="Unicode">The Unicode Consortium.
! 3352: <emph>The Unicode Standard, Version 2.0.</emph>
! 3353: Reading, Mass.: Addison-Wesley Developers Press, 1996.</bibl>
! 3354:
! 3355: </blist>
! 3356:
! 3357: </div2>
! 3358:
! 3359: <div2><head>Other References</head>
! 3360:
! 3361: <blist>
! 3362:
! 3363: <bibl id="Aho" key="Aho/Ullman">Aho, Alfred V.,
! 3364: Ravi Sethi, and Jeffrey D. Ullman.
! 3365: <emph>Compilers: Principles, Techniques, and Tools</emph>.
! 3366: Reading: Addison-Wesley, 1986, rpt. corr. 1988.</bibl>
! 3367:
! 3368: <bibl id="Berners-Lee" xml-link="simple" key="Berners-Lee et al.">
! 3369: Berners-Lee, T., R. Fielding, and L. Masinter.
! 3370: <emph>Uniform Resource Identifiers (URI): Generic Syntax and
! 3371: Semantics</emph>.
! 3372: 1997.
! 3373: (Work in progress; see updates to RFC1738.)</bibl>
! 3374:
! 3375: <bibl id="ABK" key="Brüggemann-Klein">Brüggemann-Klein, Anne.
! 3376: <emph>Regular Expressions into Finite Automata</emph>.
! 3377: Extended abstract in I. Simon, Hrsg., LATIN 1992,
! 3378: S. 97-98. Springer-Verlag, Berlin 1992.
! 3379: Full Version in Theoretical Computer Science 120: 197-213, 1993.
! 3380:
! 3381: </bibl>
! 3382:
! 3383: <bibl id="ABKDW" key="Brüggemann-Klein and Wood">Brüggemann-Klein, Anne,
! 3384: and Derick Wood.
! 3385: <emph>Deterministic Regular Languages</emph>.
! 3386: Universität Freiburg, Institut für Informatik,
! 3387: Bericht 38, Oktober 1991.
! 3388: </bibl>
! 3389:
! 3390: <bibl id="Clark" key="Clark">James Clark.
! 3391: Comparison of SGML and XML. See
! 3392: <loc href="http://www.w3.org/TR/NOTE-sgml-xml-971215">http://www.w3.org/TR/NOTE-sgml-xml-971215</loc>.
! 3393: </bibl>
! 3394: <bibl id="RFC1738" xml-link="simple" key="IETF RFC1738">
! 3395: IETF (Internet Engineering Task Force).
! 3396: <emph>RFC 1738: Uniform Resource Locators (URL)</emph>,
! 3397: ed. T. Berners-Lee, L. Masinter, M. McCahill.
! 3398: 1994.
! 3399: </bibl>
! 3400:
! 3401: <bibl id="RFC1808" xml-link="simple" key="IETF RFC1808">
! 3402: IETF (Internet Engineering Task Force).
! 3403: <emph>RFC 1808: Relative Uniform Resource Locators</emph>,
! 3404: ed. R. Fielding.
! 3405: 1995.
! 3406: </bibl>
! 3407:
! 3408: <bibl id="RFC2141" xml-link="simple" key="IETF RFC2141">
! 3409: IETF (Internet Engineering Task Force).
! 3410: <emph>RFC 2141: URN Syntax</emph>,
! 3411: ed. R. Moats.
! 3412: 1997.
! 3413: </bibl>
! 3414:
! 3415: <bibl id="ISO8879" key="ISO 8879">ISO
! 3416: (International Organization for Standardization).
! 3417: <emph>ISO 8879:1986(E). Information processing — Text and Office
! 3418: Systems — Standard Generalized Markup Language (SGML).</emph> First
! 3419: edition — 1986-10-15. [Geneva]: International Organization for
! 3420: Standardization, 1986.
! 3421: </bibl>
! 3422:
! 3423:
! 3424: <bibl id="ISO10744" key="ISO/IEC 10744">ISO
! 3425: (International Organization for Standardization).
! 3426: <emph>ISO/IEC 10744-1992 (E). Information technology —
! 3427: Hypermedia/Time-based Structuring Language (HyTime).
! 3428: </emph>
! 3429: [Geneva]: International Organization for
! 3430: Standardization, 1992.
! 3431: <emph>Extended Facilities Annexe.</emph>
! 3432: [Geneva]: International Organization for
! 3433: Standardization, 1996.
! 3434: </bibl>
! 3435:
! 3436:
! 3437:
! 3438: </blist>
! 3439: </div2>
! 3440: </div1>
! 3441: <div1 id="CharClasses">
! 3442: <head>Character Classes</head>
! 3443: <p>Following the characteristics defined in the Unicode standard,
! 3444: characters are classed as base characters (among others, these
! 3445: contain the alphabetic characters of the Latin alphabet, without
! 3446: diacritics), ideographic characters, and combining characters (among
! 3447: others, this class contains most diacritics); these classes combine
! 3448: to form the class of letters. Digits and extenders are
! 3449: also distinguished.
! 3450: <scrap lang="ebnf" id="CHARACTERS">
! 3451: <head>Characters</head>
! 3452: <prodgroup pcw3="3" pcw4="15">
! 3453: <prod id="NT-Letter"><lhs>Letter</lhs>
! 3454: <rhs><nt def="NT-BaseChar">BaseChar</nt>
! 3455: | <nt def="NT-Ideographic">Ideographic</nt></rhs> </prod>
! 3456: <prod id="NT-BaseChar"><lhs>BaseChar</lhs>
! 3457: <rhs>[#x0041-#x005A]
! 3458: | [#x0061-#x007A]
! 3459: | [#x00C0-#x00D6]
! 3460: | [#x00D8-#x00F6]
! 3461: | [#x00F8-#x00FF]
! 3462: | [#x0100-#x0131]
! 3463: | [#x0134-#x013E]
! 3464: | [#x0141-#x0148]
! 3465: | [#x014A-#x017E]
! 3466: | [#x0180-#x01C3]
! 3467: | [#x01CD-#x01F0]
! 3468: | [#x01F4-#x01F5]
! 3469: | [#x01FA-#x0217]
! 3470: | [#x0250-#x02A8]
! 3471: | [#x02BB-#x02C1]
! 3472: | #x0386
! 3473: | [#x0388-#x038A]
! 3474: | #x038C
! 3475: | [#x038E-#x03A1]
! 3476: | [#x03A3-#x03CE]
! 3477: | [#x03D0-#x03D6]
! 3478: | #x03DA
! 3479: | #x03DC
! 3480: | #x03DE
! 3481: | #x03E0
! 3482: | [#x03E2-#x03F3]
! 3483: | [#x0401-#x040C]
! 3484: | [#x040E-#x044F]
! 3485: | [#x0451-#x045C]
! 3486: | [#x045E-#x0481]
! 3487: | [#x0490-#x04C4]
! 3488: | [#x04C7-#x04C8]
! 3489: | [#x04CB-#x04CC]
! 3490: | [#x04D0-#x04EB]
! 3491: | [#x04EE-#x04F5]
! 3492: | [#x04F8-#x04F9]
! 3493: | [#x0531-#x0556]
! 3494: | #x0559
! 3495: | [#x0561-#x0586]
! 3496: | [#x05D0-#x05EA]
! 3497: | [#x05F0-#x05F2]
! 3498: | [#x0621-#x063A]
! 3499: | [#x0641-#x064A]
! 3500: | [#x0671-#x06B7]
! 3501: | [#x06BA-#x06BE]
! 3502: | [#x06C0-#x06CE]
! 3503: | [#x06D0-#x06D3]
! 3504: | #x06D5
! 3505: | [#x06E5-#x06E6]
! 3506: | [#x0905-#x0939]
! 3507: | #x093D
! 3508: | [#x0958-#x0961]
! 3509: | [#x0985-#x098C]
! 3510: | [#x098F-#x0990]
! 3511: | [#x0993-#x09A8]
! 3512: | [#x09AA-#x09B0]
! 3513: | #x09B2
! 3514: | [#x09B6-#x09B9]
! 3515: | [#x09DC-#x09DD]
! 3516: | [#x09DF-#x09E1]
! 3517: | [#x09F0-#x09F1]
! 3518: | [#x0A05-#x0A0A]
! 3519: | [#x0A0F-#x0A10]
! 3520: | [#x0A13-#x0A28]
! 3521: | [#x0A2A-#x0A30]
! 3522: | [#x0A32-#x0A33]
! 3523: | [#x0A35-#x0A36]
! 3524: | [#x0A38-#x0A39]
! 3525: | [#x0A59-#x0A5C]
! 3526: | #x0A5E
! 3527: | [#x0A72-#x0A74]
! 3528: | [#x0A85-#x0A8B]
! 3529: | #x0A8D
! 3530: | [#x0A8F-#x0A91]
! 3531: | [#x0A93-#x0AA8]
! 3532: | [#x0AAA-#x0AB0]
! 3533: | [#x0AB2-#x0AB3]
! 3534: | [#x0AB5-#x0AB9]
! 3535: | #x0ABD
! 3536: | #x0AE0
! 3537: | [#x0B05-#x0B0C]
! 3538: | [#x0B0F-#x0B10]
! 3539: | [#x0B13-#x0B28]
! 3540: | [#x0B2A-#x0B30]
! 3541: | [#x0B32-#x0B33]
! 3542: | [#x0B36-#x0B39]
! 3543: | #x0B3D
! 3544: | [#x0B5C-#x0B5D]
! 3545: | [#x0B5F-#x0B61]
! 3546: | [#x0B85-#x0B8A]
! 3547: | [#x0B8E-#x0B90]
! 3548: | [#x0B92-#x0B95]
! 3549: | [#x0B99-#x0B9A]
! 3550: | #x0B9C
! 3551: | [#x0B9E-#x0B9F]
! 3552: | [#x0BA3-#x0BA4]
! 3553: | [#x0BA8-#x0BAA]
! 3554: | [#x0BAE-#x0BB5]
! 3555: | [#x0BB7-#x0BB9]
! 3556: | [#x0C05-#x0C0C]
! 3557: | [#x0C0E-#x0C10]
! 3558: | [#x0C12-#x0C28]
! 3559: | [#x0C2A-#x0C33]
! 3560: | [#x0C35-#x0C39]
! 3561: | [#x0C60-#x0C61]
! 3562: | [#x0C85-#x0C8C]
! 3563: | [#x0C8E-#x0C90]
! 3564: | [#x0C92-#x0CA8]
! 3565: | [#x0CAA-#x0CB3]
! 3566: | [#x0CB5-#x0CB9]
! 3567: | #x0CDE
! 3568: | [#x0CE0-#x0CE1]
! 3569: | [#x0D05-#x0D0C]
! 3570: | [#x0D0E-#x0D10]
! 3571: | [#x0D12-#x0D28]
! 3572: | [#x0D2A-#x0D39]
! 3573: | [#x0D60-#x0D61]
! 3574: | [#x0E01-#x0E2E]
! 3575: | #x0E30
! 3576: | [#x0E32-#x0E33]
! 3577: | [#x0E40-#x0E45]
! 3578: | [#x0E81-#x0E82]
! 3579: | #x0E84
! 3580: | [#x0E87-#x0E88]
! 3581: | #x0E8A
! 3582: | #x0E8D
! 3583: | [#x0E94-#x0E97]
! 3584: | [#x0E99-#x0E9F]
! 3585: | [#x0EA1-#x0EA3]
! 3586: | #x0EA5
! 3587: | #x0EA7
! 3588: | [#x0EAA-#x0EAB]
! 3589: | [#x0EAD-#x0EAE]
! 3590: | #x0EB0
! 3591: | [#x0EB2-#x0EB3]
! 3592: | #x0EBD
! 3593: | [#x0EC0-#x0EC4]
! 3594: | [#x0F40-#x0F47]
! 3595: | [#x0F49-#x0F69]
! 3596: | [#x10A0-#x10C5]
! 3597: | [#x10D0-#x10F6]
! 3598: | #x1100
! 3599: | [#x1102-#x1103]
! 3600: | [#x1105-#x1107]
! 3601: | #x1109
! 3602: | [#x110B-#x110C]
! 3603: | [#x110E-#x1112]
! 3604: | #x113C
! 3605: | #x113E
! 3606: | #x1140
! 3607: | #x114C
! 3608: | #x114E
! 3609: | #x1150
! 3610: | [#x1154-#x1155]
! 3611: | #x1159
! 3612: | [#x115F-#x1161]
! 3613: | #x1163
! 3614: | #x1165
! 3615: | #x1167
! 3616: | #x1169
! 3617: | [#x116D-#x116E]
! 3618: | [#x1172-#x1173]
! 3619: | #x1175
! 3620: | #x119E
! 3621: | #x11A8
! 3622: | #x11AB
! 3623: | [#x11AE-#x11AF]
! 3624: | [#x11B7-#x11B8]
! 3625: | #x11BA
! 3626: | [#x11BC-#x11C2]
! 3627: | #x11EB
! 3628: | #x11F0
! 3629: | #x11F9
! 3630: | [#x1E00-#x1E9B]
! 3631: | [#x1EA0-#x1EF9]
! 3632: | [#x1F00-#x1F15]
! 3633: | [#x1F18-#x1F1D]
! 3634: | [#x1F20-#x1F45]
! 3635: | [#x1F48-#x1F4D]
! 3636: | [#x1F50-#x1F57]
! 3637: | #x1F59
! 3638: | #x1F5B
! 3639: | #x1F5D
! 3640: | [#x1F5F-#x1F7D]
! 3641: | [#x1F80-#x1FB4]
! 3642: | [#x1FB6-#x1FBC]
! 3643: | #x1FBE
! 3644: | [#x1FC2-#x1FC4]
! 3645: | [#x1FC6-#x1FCC]
! 3646: | [#x1FD0-#x1FD3]
! 3647: | [#x1FD6-#x1FDB]
! 3648: | [#x1FE0-#x1FEC]
! 3649: | [#x1FF2-#x1FF4]
! 3650: | [#x1FF6-#x1FFC]
! 3651: | #x2126
! 3652: | [#x212A-#x212B]
! 3653: | #x212E
! 3654: | [#x2180-#x2182]
! 3655: | [#x3041-#x3094]
! 3656: | [#x30A1-#x30FA]
! 3657: | [#x3105-#x312C]
! 3658: | [#xAC00-#xD7A3]
! 3659: </rhs></prod>
! 3660: <prod id="NT-Ideographic"><lhs>Ideographic</lhs>
! 3661: <rhs>[#x4E00-#x9FA5]
! 3662: | #x3007
! 3663: | [#x3021-#x3029]
! 3664: </rhs></prod>
! 3665: <prod id="NT-CombiningChar"><lhs>CombiningChar</lhs>
! 3666: <rhs>[#x0300-#x0345]
! 3667: | [#x0360-#x0361]
! 3668: | [#x0483-#x0486]
! 3669: | [#x0591-#x05A1]
! 3670: | [#x05A3-#x05B9]
! 3671: | [#x05BB-#x05BD]
! 3672: | #x05BF
! 3673: | [#x05C1-#x05C2]
! 3674: | #x05C4
! 3675: | [#x064B-#x0652]
! 3676: | #x0670
! 3677: | [#x06D6-#x06DC]
! 3678: | [#x06DD-#x06DF]
! 3679: | [#x06E0-#x06E4]
! 3680: | [#x06E7-#x06E8]
! 3681: | [#x06EA-#x06ED]
! 3682: | [#x0901-#x0903]
! 3683: | #x093C
! 3684: | [#x093E-#x094C]
! 3685: | #x094D
! 3686: | [#x0951-#x0954]
! 3687: | [#x0962-#x0963]
! 3688: | [#x0981-#x0983]
! 3689: | #x09BC
! 3690: | #x09BE
! 3691: | #x09BF
! 3692: | [#x09C0-#x09C4]
! 3693: | [#x09C7-#x09C8]
! 3694: | [#x09CB-#x09CD]
! 3695: | #x09D7
! 3696: | [#x09E2-#x09E3]
! 3697: | #x0A02
! 3698: | #x0A3C
! 3699: | #x0A3E
! 3700: | #x0A3F
! 3701: | [#x0A40-#x0A42]
! 3702: | [#x0A47-#x0A48]
! 3703: | [#x0A4B-#x0A4D]
! 3704: | [#x0A70-#x0A71]
! 3705: | [#x0A81-#x0A83]
! 3706: | #x0ABC
! 3707: | [#x0ABE-#x0AC5]
! 3708: | [#x0AC7-#x0AC9]
! 3709: | [#x0ACB-#x0ACD]
! 3710: | [#x0B01-#x0B03]
! 3711: | #x0B3C
! 3712: | [#x0B3E-#x0B43]
! 3713: | [#x0B47-#x0B48]
! 3714: | [#x0B4B-#x0B4D]
! 3715: | [#x0B56-#x0B57]
! 3716: | [#x0B82-#x0B83]
! 3717: | [#x0BBE-#x0BC2]
! 3718: | [#x0BC6-#x0BC8]
! 3719: | [#x0BCA-#x0BCD]
! 3720: | #x0BD7
! 3721: | [#x0C01-#x0C03]
! 3722: | [#x0C3E-#x0C44]
! 3723: | [#x0C46-#x0C48]
! 3724: | [#x0C4A-#x0C4D]
! 3725: | [#x0C55-#x0C56]
! 3726: | [#x0C82-#x0C83]
! 3727: | [#x0CBE-#x0CC4]
! 3728: | [#x0CC6-#x0CC8]
! 3729: | [#x0CCA-#x0CCD]
! 3730: | [#x0CD5-#x0CD6]
! 3731: | [#x0D02-#x0D03]
! 3732: | [#x0D3E-#x0D43]
! 3733: | [#x0D46-#x0D48]
! 3734: | [#x0D4A-#x0D4D]
! 3735: | #x0D57
! 3736: | #x0E31
! 3737: | [#x0E34-#x0E3A]
! 3738: | [#x0E47-#x0E4E]
! 3739: | #x0EB1
! 3740: | [#x0EB4-#x0EB9]
! 3741: | [#x0EBB-#x0EBC]
! 3742: | [#x0EC8-#x0ECD]
! 3743: | [#x0F18-#x0F19]
! 3744: | #x0F35
! 3745: | #x0F37
! 3746: | #x0F39
! 3747: | #x0F3E
! 3748: | #x0F3F
! 3749: | [#x0F71-#x0F84]
! 3750: | [#x0F86-#x0F8B]
! 3751: | [#x0F90-#x0F95]
! 3752: | #x0F97
! 3753: | [#x0F99-#x0FAD]
! 3754: | [#x0FB1-#x0FB7]
! 3755: | #x0FB9
! 3756: | [#x20D0-#x20DC]
! 3757: | #x20E1
! 3758: | [#x302A-#x302F]
! 3759: | #x3099
! 3760: | #x309A
! 3761: </rhs></prod>
! 3762: <prod id="NT-Digit"><lhs>Digit</lhs>
! 3763: <rhs>[#x0030-#x0039]
! 3764: | [#x0660-#x0669]
! 3765: | [#x06F0-#x06F9]
! 3766: | [#x0966-#x096F]
! 3767: | [#x09E6-#x09EF]
! 3768: | [#x0A66-#x0A6F]
! 3769: | [#x0AE6-#x0AEF]
! 3770: | [#x0B66-#x0B6F]
! 3771: | [#x0BE7-#x0BEF]
! 3772: | [#x0C66-#x0C6F]
! 3773: | [#x0CE6-#x0CEF]
! 3774: | [#x0D66-#x0D6F]
! 3775: | [#x0E50-#x0E59]
! 3776: | [#x0ED0-#x0ED9]
! 3777: | [#x0F20-#x0F29]
! 3778: </rhs></prod>
! 3779: <prod id="NT-Extender"><lhs>Extender</lhs>
! 3780: <rhs>#x00B7
! 3781: | #x02D0
! 3782: | #x02D1
! 3783: | #x0387
! 3784: | #x0640
! 3785: | #x0E46
! 3786: | #x0EC6
! 3787: | #x3005
! 3788: | [#x3031-#x3035]
! 3789: | [#x309D-#x309E]
! 3790: | [#x30FC-#x30FE]
! 3791: </rhs></prod>
! 3792:
! 3793: </prodgroup>
! 3794: </scrap>
! 3795: </p>
! 3796: <p>The character classes defined here can be derived from the
! 3797: Unicode character database as follows:
! 3798: <ulist>
! 3799: <item>
! 3800: <p>Name start characters must have one of the categories Ll, Lu,
! 3801: Lo, Lt, Nl.</p>
! 3802: </item>
! 3803: <item>
! 3804: <p>Name characters other than Name-start characters
! 3805: must have one of the categories Mc, Me, Mn, Lm, or Nd.</p>
! 3806: </item>
! 3807: <item>
! 3808: <p>Characters in the compatibility area (i.e. with character code
! 3809: greater than #xF900 and less than #xFFFE) are not allowed in XML
! 3810: names.</p>
! 3811: </item>
! 3812: <item>
! 3813: <p>Characters which have a font or compatibility decomposition (i.e. those
! 3814: with a "compatibility formatting tag" in field 5 of the database --
! 3815: marked by field 5 beginning with a "<") are not allowed.</p>
! 3816: </item>
! 3817: <item>
! 3818: <p>The following characters are treated as name-start characters
! 3819: rather than name characters, because the property file classifies
! 3820: them as Alphabetic: [#x02BB-#x02C1], #x0559, #x06E5, #x06E6.</p>
! 3821: </item>
! 3822: <item>
! 3823: <p>Characters #x20DD-#x20E0 are excluded (in accordance with
! 3824: Unicode, section 5.14).</p>
! 3825: </item>
! 3826: <item>
! 3827: <p>Character #x00B7 is classified as an extender, because the
! 3828: property list so identifies it.</p>
! 3829: </item>
! 3830: <item>
! 3831: <p>Character #x0387 is added as a name character, because #x00B7
! 3832: is its canonical equivalent.</p>
! 3833: </item>
! 3834: <item>
! 3835: <p>Characters ':' and '_' are allowed as name-start characters.</p>
! 3836: </item>
! 3837: <item>
! 3838: <p>Characters '-' and '.' are allowed as name characters.</p>
! 3839: </item>
! 3840: </ulist>
! 3841: </p>
! 3842: </div1>
! 3843: <inform-div1 id="sec-xml-and-sgml">
! 3844: <head>XML and SGML</head>
! 3845:
! 3846: <p>XML is designed to be a subset of SGML, in that every
! 3847: <termref def="dt-valid">valid</termref> XML document should also be a
! 3848: conformant SGML document.
! 3849: For a detailed comparison of the additional restrictions that XML places on
! 3850: documents beyond those of SGML, see <bibref ref="Clark"/>.
! 3851: </p>
! 3852: </inform-div1>
! 3853: <inform-div1 id="sec-entexpand">
! 3854: <head>Expansion of Entity and Character References</head>
! 3855: <p>This appendix contains some examples illustrating the
! 3856: sequence of entity- and character-reference recognition and
! 3857: expansion, as specified in <specref ref="entproc"/>.</p>
! 3858: <p>
! 3859: If the DTD contains the declaration
! 3860: <eg><![CDATA[<!ENTITY example "<p>An ampersand (&#38;) may be escaped
! 3861: numerically (&#38;#38;) or with a general entity
! 3862: (&amp;).</p>" >
! 3863: ]]></eg>
! 3864: then the XML processor will recognize the character references
! 3865: when it parses the entity declaration, and resolve them before
! 3866: storing the following string as the
! 3867: value of the entity "<code>example</code>":
! 3868: <eg><![CDATA[<p>An ampersand (&) may be escaped
! 3869: numerically (&#38;) or with a general entity
! 3870: (&amp;).</p>
! 3871: ]]></eg>
! 3872: A reference in the document to "<code>&example;</code>"
! 3873: will cause the text to be reparsed, at which time the
! 3874: start- and end-tags of the "<code>p</code>" element will be recognized
! 3875: and the three references will be recognized and expanded,
! 3876: resulting in a "<code>p</code>" element with the following content
! 3877: (all data, no delimiters or markup):
! 3878: <eg><![CDATA[An ampersand (&) may be escaped
! 3879: numerically (&) or with a general entity
! 3880: (&).
! 3881: ]]></eg>
! 3882: </p>
! 3883: <p>A more complex example will illustrate the rules and their
! 3884: effects fully. In the following example, the line numbers are
! 3885: solely for reference.
! 3886: <eg><![CDATA[1 <?xml version='1.0'?>
! 3887: 2 <!DOCTYPE test [
! 3888: 3 <!ELEMENT test (#PCDATA) >
! 3889: 4 <!ENTITY % xx '%zz;'>
! 3890: 5 <!ENTITY % zz '<!ENTITY tricky "error-prone" >' >
! 3891: 6 %xx;
! 3892: 7 ]>
! 3893: 8 <test>This sample shows a &tricky; method.</test>
! 3894: ]]></eg>
! 3895: This produces the following:
! 3896: <ulist spacing="compact">
! 3897: <item><p>in line 4, the reference to character 37 is expanded immediately,
! 3898: and the parameter entity "<code>xx</code>" is stored in the symbol
! 3899: table with the value "<code>%zz;</code>". Since the replacement text
! 3900: is not rescanned, the reference to parameter entity "<code>zz</code>"
! 3901: is not recognized. (And it would be an error if it were, since
! 3902: "<code>zz</code>" is not yet declared.)</p></item>
! 3903: <item><p>in line 5, the character reference "<code>&#60;</code>" is
! 3904: expanded immediately and the parameter entity "<code>zz</code>" is
! 3905: stored with the replacement text
! 3906: "<code><!ENTITY tricky "error-prone" ></code>",
! 3907: which is a well-formed entity declaration.</p></item>
! 3908: <item><p>in line 6, the reference to "<code>xx</code>" is recognized,
! 3909: and the replacement text of "<code>xx</code>" (namely
! 3910: "<code>%zz;</code>") is parsed. The reference to "<code>zz</code>"
! 3911: is recognized in its turn, and its replacement text
! 3912: ("<code><!ENTITY tricky "error-prone" ></code>") is parsed.
! 3913: The general entity "<code>tricky</code>" has now been
! 3914: declared, with the replacement text "<code>error-prone</code>".</p></item>
! 3915: <item><p>
! 3916: in line 8, the reference to the general entity "<code>tricky</code>" is
! 3917: recognized, and it is expanded, so the full content of the
! 3918: "<code>test</code>" element is the self-describing (and ungrammatical) string
! 3919: <emph>This sample shows a error-prone method.</emph>
! 3920: </p></item>
! 3921: </ulist>
! 3922: </p>
! 3923: </inform-div1>
! 3924: <inform-div1 id="determinism">
! 3925: <head>Deterministic Content Models</head>
! 3926: <p><termref def="dt-compat">For compatibility</termref>, it is
! 3927: required
! 3928: that content models in element type declarations be deterministic.
! 3929: </p>
! 3930: <!-- FINAL EDIT: WebSGML allows ambiguity? -->
! 3931: <p>SGML
! 3932: requires deterministic content models (it calls them
! 3933: "unambiguous"); XML processors built using SGML systems may
! 3934: flag non-deterministic content models as errors.</p>
! 3935: <p>For example, the content model <code>((b, c) | (b, d))</code> is
! 3936: non-deterministic, because given an initial <code>b</code> the parser
! 3937: cannot know which <code>b</code> in the model is being matched without
! 3938: looking ahead to see which element follows the <code>b</code>.
! 3939: In this case, the two references to
! 3940: <code>b</code> can be collapsed
! 3941: into a single reference, making the model read
! 3942: <code>(b, (c | d))</code>. An initial <code>b</code> now clearly
! 3943: matches only a single name in the content model. The parser doesn't
! 3944: need to look ahead to see what follows; either <code>c</code> or
! 3945: <code>d</code> would be accepted.</p>
! 3946: <p>More formally: a finite state automaton may be constructed from the
! 3947: content model using the standard algorithms, e.g. algorithm 3.5
! 3948: in section 3.9
! 3949: of Aho, Sethi, and Ullman <bibref ref="Aho"/>.
! 3950: In many such algorithms, a follow set is constructed for each
! 3951: position in the regular expression (i.e., each leaf
! 3952: node in the
! 3953: syntax tree for the regular expression);
! 3954: if any position has a follow set in which
! 3955: more than one following position is
! 3956: labeled with the same element type name,
! 3957: then the content model is in error
! 3958: and may be reported as an error.
! 3959: </p>
! 3960: <p>Algorithms exist which allow many but not all non-deterministic
! 3961: content models to be reduced automatically to equivalent deterministic
! 3962: models; see Brüggemann-Klein 1991 <bibref ref="ABK"/>.</p>
! 3963: </inform-div1>
! 3964: <inform-div1 id="sec-guessing">
! 3965: <head>Autodetection of Character Encodings</head>
! 3966: <p>The XML encoding declaration functions as an internal label on each
! 3967: entity, indicating which character encoding is in use. Before an XML
! 3968: processor can read the internal label, however, it apparently has to
! 3969: know what character encoding is in use—which is what the internal label
! 3970: is trying to indicate. In the general case, this is a hopeless
! 3971: situation. It is not entirely hopeless in XML, however, because XML
! 3972: limits the general case in two ways: each implementation is assumed
! 3973: to support only a finite set of character encodings, and the XML
! 3974: encoding declaration is restricted in position and content in order to
! 3975: make it feasible to autodetect the character encoding in use in each
! 3976: entity in normal cases. Also, in many cases other sources of information
! 3977: are available in addition to the XML data stream itself.
! 3978: Two cases may be distinguished,
! 3979: depending on whether the XML entity is presented to the
! 3980: processor without, or with, any accompanying
! 3981: (external) information. We consider the first case first.
! 3982: </p>
! 3983: <p>
! 3984: Because each XML entity not in UTF-8 or UTF-16 format <emph>must</emph>
! 3985: begin with an XML encoding declaration, in which the first characters
! 3986: must be '<code><?xml</code>', any conforming processor can detect,
! 3987: after two to four octets of input, which of the following cases apply.
! 3988: In reading this list, it may help to know that in UCS-4, '<' is
! 3989: "<code>#x0000003C</code>" and '?' is "<code>#x0000003F</code>", and the Byte
! 3990: Order Mark required of UTF-16 data streams is "<code>#xFEFF</code>".</p>
! 3991: <p>
! 3992: <ulist>
! 3993: <item>
! 3994: <p><code>00 00 00 3C</code>: UCS-4, big-endian machine (1234 order)</p>
! 3995: </item>
! 3996: <item>
! 3997: <p><code>3C 00 00 00</code>: UCS-4, little-endian machine (4321 order)</p>
! 3998: </item>
! 3999: <item>
! 4000: <p><code>00 00 3C 00</code>: UCS-4, unusual octet order (2143)</p>
! 4001: </item>
! 4002: <item>
! 4003: <p><code>00 3C 00 00</code>: UCS-4, unusual octet order (3412)</p>
! 4004: </item>
! 4005: <item>
! 4006: <p><code>FE FF</code>: UTF-16, big-endian</p>
! 4007: </item>
! 4008: <item>
! 4009: <p><code>FF FE</code>: UTF-16, little-endian</p>
! 4010: </item>
! 4011: <item>
! 4012: <p><code>00 3C 00 3F</code>: UTF-16, big-endian, no Byte Order Mark
! 4013: (and thus, strictly speaking, in error)</p>
! 4014: </item>
! 4015: <item>
! 4016: <p><code>3C 00 3F 00</code>: UTF-16, little-endian, no Byte Order Mark
! 4017: (and thus, strictly speaking, in error)</p>
! 4018: </item>
! 4019: <item>
! 4020: <p><code>3C 3F 78 6D</code>: UTF-8, ISO 646, ASCII, some part of ISO 8859,
! 4021: Shift-JIS, EUC, or any other 7-bit, 8-bit, or mixed-width encoding
! 4022: which ensures that the characters of ASCII have their normal positions,
! 4023: width,
! 4024: and values; the actual encoding declaration must be read to
! 4025: detect which of these applies, but since all of these encodings
! 4026: use the same bit patterns for the ASCII characters, the encoding
! 4027: declaration itself may be read reliably
! 4028: </p>
! 4029: </item>
! 4030: <item>
! 4031: <p><code>4C 6F A7 94</code>: EBCDIC (in some flavor; the full
! 4032: encoding declaration must be read to tell which code page is in
! 4033: use)</p>
! 4034: </item>
! 4035: <item>
! 4036: <p>other: UTF-8 without an encoding declaration, or else
! 4037: the data stream is corrupt, fragmentary, or enclosed in
! 4038: a wrapper of some kind</p>
! 4039: </item>
! 4040: </ulist>
! 4041: </p>
! 4042: <p>
! 4043: This level of autodetection is enough to read the XML encoding
! 4044: declaration and parse the character-encoding identifier, which is
! 4045: still necessary to distinguish the individual members of each family
! 4046: of encodings (e.g. to tell UTF-8 from 8859, and the parts of 8859
! 4047: from each other, or to distinguish the specific EBCDIC code page in
! 4048: use, and so on).
! 4049: </p>
! 4050: <p>
! 4051: Because the contents of the encoding declaration are restricted to
! 4052: ASCII characters, a processor can reliably read the entire encoding
! 4053: declaration as soon as it has detected which family of encodings is in
! 4054: use. Since in practice, all widely used character encodings fall into
! 4055: one of the categories above, the XML encoding declaration allows
! 4056: reasonably reliable in-band labeling of character encodings, even when
! 4057: external sources of information at the operating-system or
! 4058: transport-protocol level are unreliable.
! 4059: </p>
! 4060: <p>
! 4061: Once the processor has detected the character encoding in use, it can
! 4062: act appropriately, whether by invoking a separate input routine for
! 4063: each case, or by calling the proper conversion function on each
! 4064: character of input.
! 4065: </p>
! 4066: <p>
! 4067: Like any self-labeling system, the XML encoding declaration will not
! 4068: work if any software changes the entity's character set or encoding
! 4069: without updating the encoding declaration. Implementors of
! 4070: character-encoding routines should be careful to ensure the accuracy
! 4071: of the internal and external information used to label the entity.
! 4072: </p>
! 4073: <p>The second possible case occurs when the XML entity is accompanied
! 4074: by encoding information, as in some file systems and some network
! 4075: protocols.
! 4076: When multiple sources of information are available,
! 4077:
! 4078: their relative
! 4079: priority and the preferred method of handling conflict should be
! 4080: specified as part of the higher-level protocol used to deliver XML.
! 4081: Rules for the relative priority of the internal label and the
! 4082: MIME-type label in an external header, for example, should be part of the
! 4083: RFC document defining the text/xml and application/xml MIME types. In
! 4084: the interests of interoperability, however, the following rules
! 4085: are recommended.
! 4086: <ulist>
! 4087: <item><p>If an XML entity is in a file, the Byte-Order Mark
! 4088: and encoding-declaration PI are used (if present) to determine the
! 4089: character encoding. All other heuristics and sources of information
! 4090: are solely for error recovery.
! 4091: </p></item>
! 4092: <item><p>If an XML entity is delivered with a
! 4093: MIME type of text/xml, then the <code>charset</code> parameter
! 4094: on the MIME type determines the
! 4095: character encoding method; all other heuristics and sources of
! 4096: information are solely for error recovery.
! 4097: </p></item>
! 4098: <item><p>If an XML entity is delivered
! 4099: with a
! 4100: MIME type of application/xml, then the Byte-Order Mark and
! 4101: encoding-declaration PI are used (if present) to determine the
! 4102: character encoding. All other heuristics and sources of
! 4103: information are solely for error recovery.
! 4104: </p></item>
! 4105: </ulist>
! 4106: These rules apply only in the absence of protocol-level documentation;
! 4107: in particular, when the MIME types text/xml and application/xml are
! 4108: defined, the recommendations of the relevant RFC will supersede
! 4109: these rules.
! 4110: </p>
! 4111:
! 4112: </inform-div1>
! 4113:
! 4114: <inform-div1 id="sec-xml-wg">
! 4115: <head>W3C XML Working Group</head>
! 4116:
! 4117: <p>This specification was prepared and approved for publication by the
! 4118: W3C XML Working Group (WG). WG approval of this specification does
! 4119: not necessarily imply that all WG members voted for its approval.
! 4120: The current and former members of the XML WG are:</p>
! 4121:
! 4122: <orglist>
! 4123: <member><name>Jon Bosak, Sun</name><role>Chair</role></member>
! 4124: <member><name>James Clark</name><role>Technical Lead</role></member>
! 4125: <member><name>Tim Bray, Textuality and Netscape</name><role>XML Co-editor</role></member>
! 4126: <member><name>Jean Paoli, Microsoft</name><role>XML Co-editor</role></member>
! 4127: <member><name>C. M. Sperberg-McQueen, U. of Ill.</name><role>XML
! 4128: Co-editor</role></member>
! 4129: <member><name>Dan Connolly, W3C</name><role>W3C Liaison</role></member>
! 4130: <member><name>Paula Angerstein, Texcel</name></member>
! 4131: <member><name>Steve DeRose, INSO</name></member>
! 4132: <member><name>Dave Hollander, HP</name></member>
! 4133: <member><name>Eliot Kimber, ISOGEN</name></member>
! 4134: <member><name>Eve Maler, ArborText</name></member>
! 4135: <member><name>Tom Magliery, NCSA</name></member>
! 4136: <member><name>Murray Maloney, Muzmo and Grif</name></member>
! 4137: <member><name>Makoto Murata, Fuji Xerox Information Systems</name></member>
! 4138: <member><name>Joel Nava, Adobe</name></member>
! 4139: <member><name>Conleth O'Connell, Vignette</name></member>
! 4140: <member><name>Peter Sharpe, SoftQuad</name></member>
! 4141: <member><name>John Tigue, DataChannel</name></member>
! 4142: </orglist>
! 4143:
! 4144: </inform-div1>
! 4145: </back>
! 4146: </spec>
! 4147: <!-- Keep this comment at the end of the file
! 4148: Local variables:
! 4149: mode: sgml
! 4150: sgml-default-dtd-file:"~/sgml/spec.ced"
! 4151: sgml-omittag:t
! 4152: sgml-shorttag:t
! 4153: End:
! 4154: -->
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