The "split" format is for a separating the gui from the main program. The main program can be installed setuid, and you don't want to link a gui-library with a setuid program. The split format is: The "raw" format is: hostline|pingline|dnsline|timestampline hostline: h pingline: p dnsline: d timestampline: t Timestampline is not yet implemented. Need to find out how to do ICMP timestamping first. :-) Someone suggested to put the following text here. As to context: Some people are wondering why mtr sometimes reports hosts beyond the destination host. The FINAL host will occasionally be mentioned at position n, n+1, n+2 etc. You know traceroute, right? It sends a packet, waits for the reply to come back and when it comes back, it sends the next packet. If say hosts 5-8 do not send "time exceeded" packets, you'll wait a 4*3 = twelve seconds extra before you get any results on hosts 9 and further. MTR doesn't work like that. In theory we could send out a probe for host 1-40 all at once. But this would pose an unnecessary burden on the network. So what we do, is we send out probes for a max of 5 hosts beyond where we've seen a reply. So in the example above, we'd see a reply from router at position 4, then we'd send out 5-9 (and because the max-host is now at 9, we'll send them out at 1s/9 = 111ms intervals). When the reply from host 9 comes back, we'll start probing for host 10-15 (at about 60ms intervals). But suppose the network delay upto host 9 is already 200ms and suppose our destination host is at position 11. Then by the time the packet from host 11 comes back, we'll already have sent probe packets for position 12, 13, and 14! Those will come back as "destination reached" and be reported by the "raw" mode. Curses mode will stop showing hosts with position numbers beyond the first reply of the destination host. It could gather the information about replies to packets sent as probes FURTHER than it actually is into the line displayed at its true position, but it doesn't (yet). In fact the above example is almost completely true: % mtr -r -n -c 2 152.179.99.218 | tail -5 13.|-- 144.232.18.238 0.0% 2 94.8 95.4 94.8 96.0 0.8 14.|-- 152.63.16.182 0.0% 2 95.1 95.5 95.1 95.8 0.5 15.|-- 152.63.64.106 0.0% 2 163.9 163.9 163.9 164.0 0.1 16.|-- 152.63.50.89 50.0% 2 163.7 163.7 163.7 163.7 0.0 17.|-- 152.179.99.218 50.0% 2 168.2 168.2 168.2 168.2 0.0 % mtr -l -c 2 152.179.99.218 | grep -v "^[dp]" |tail -7 h 10 144.232.1.41 h 11 144.232.4.96 h 16 152.179.99.218 h 17 152.179.99.218 h 18 152.179.99.218 h 12 144.232.18.238 h 13 152.63.16.182 As you can see we get the reply from the destination host at position 16 AFTER we've sent probes for position 17 and 18. When those come back, they are reported. That's what raw mode does. It reports the raw information. If you write a backend for the raw mode, it's up to you to filter/display the results. h 10 144.232.1.41 h 11 144.232.4.96 h 12 144.232.18.238 h 13 152.63.16.182 h 14 152.63.64.106 h 15 152.63.50.89 h 16 152.179.99.218 h 17 152.179.99.218 h 18 152.179.99.218