There's been a bit of a discussion in some threads recently on how to log tube stock so I thought that I'd try to set out one way of logging tube stock. The generally accepted way to do this is to record the outer numbers of the train unless there is a lower numbered car elsewhere in that half of the train, so for example on the Victoria line, you would record 11001+11002 but this falls over on some lines so I'll go through the network, line by line Bakerloo - is operated by 1972 tube stock in seven car formations comprising a double cab four car unit at the Elephant & Castle end of the train and a single cab three car unit at the Queens Park/Harrow end of the train. The number of the three car unit bears no relation to the four car unit. Recording outer end numbers would give you say 3237+3543 but the lowest numbered car in a three car set is in the 34xx series so to follow the protocal laid out above, you'd actually record 3237+3443 Central - is operated by 1992 tube stock in eight car formations. Each eight car unit is made up of four two car units and only the end units will have cabs. The outer two cars at each end of the unit should be odd numbered while the middle four will be even numbered. The best way of logging all these is to record the 92xxx numbered cars so for example 92159+92428+92074+92231. If you say log a 91xxx car instead of the 92xxx car, there is a relationship between the two so simply change your 91xxx number to 92xxx. The existance of the Hainault loop will mean that sets can operate eith way around. Note that there are a few odd numbered units, 92319 is one, that have been reconfigured to run in the middle of sets, i.e. as if they were cabless even numbered units. Jubilee - is operated by seven car sets of 1996 tube stock comprising a four car unit at the Stratford end (odd numbers) and a three car unit (even numbers) at the Stanmore end. These units are not permanently paired so following maintenance units can swap partners. The outer cars of all the units are the lowest numbered so you might record 96001+96054. But if you revisit the Jubilee in a year's time, do not assume that 96001 is still coupled to 96054. Northern - is operated by six car units of 1995 tube stock comprising two three car units which until recently have been semi-permanently coupled together. However, recent overhauls have seen some shuffling of the pack. There is a thread here that discusses the current formations. There is generally a direct relationship between the two "half" units e.g. 51511 runs with 51512 but this is compromised by the 26 de-icing units that were randomly inserted into the formations - these are numbered in the 517xx series. Safe thing to record is both outer units, e.g. 51501+51701. Also because of the Kennington loop, it is not possible to determine which end of the unit will be south facing and vice versa. Piccadilly - is operated by six car sets of 1973 tube stock comprising two three car "half" units. Most are single cab units numbered in the 1xx or 2xx series. So you might record 101+234. However, there are also some double cab three car units numbered in the 8xx series. These will normally operate with a single cab unit so you will end up with a cab in the middle -but beware, the units contain both even and odd numbered cabs and either can be the outer end! 870 will be always paired with 871, 872 with 873 etc. with one exception whose identity escapes me (possibly 884) where because of collision damage, part of a half cab unit runs with part of a double-cab unit. If you log say 143+871 then a few days later 143+870, you will have ridden on exactly the same train. The protocol seems to dictate that for double cab units, you record the even numbered cab irrespective of where it is in the train. Two double cab units together are possible but extremely rare. Victoria - is operated by eight car units of 2009 tube stock. These currently operate in fixed formations so recording the outer two cars, e.g. 11053+11054 will ensure that you have both halves of the unit recorded properly. Circle, Hammersmith & City, District - the Circle, H&C and increasingly the District is operated by the seven car S-7 sub surface stock. These at present are permanently couple three and four car sets. Even numbers will be at one end, odd the other so you might log 21301+21302 or 21505+21506. The existance of traingles at Earls Court and Aldgate mean that it is not possible to determine which end of the train is odd numbered etc. District - the main line is still predominantly operated by the six car D78 sub surface stock although by the end of 2016 it will all be gone. A six car unit will comprise two half sets and the outer cabs will normally be 70xx or 71xx. The even numbered half is at the west end, odd at the east. There are also 15 three car double cab units (numbered 75xx) which can replace either a 70xx or 71xx unit. One end of a double cab unit will be even, the other odd (e.g. 7504 and 7505). For recording purposes, sample logs would show 7000+7129 or 7043+7504. If you saw say 7030 with 7505 a few week later, then 7505 is the same as 7504 and the usual protocol would say record the latter as 7030+7504 even though 7504 ws in the middle of the set. There are no permanent formations and two double cab units together are a rarity. Metropolitan - is operated by 58 sets of eight car S-8 sub surface stock. These are outwardly similar to the S-7 stock. The existance of the traingle near Moor Park means that there is no way of determining which end of a set is even numbered etc. As with all modern underground stock, they are intended to be in fixed formation so you'll end up with can 21001 on one end and 21002 on the other, then 21003 with 21004 and so on. So easy to record 21001+21002, 21003+21004. There are a few S-7 sets currently running on the Met with and additional trailer - these are refererred to as S-7+1 sets so you might have 21381+21382. Hopefully this helps folk record their underground stock but feel free to pitch in with your thoughts, enhancements, alternative ways of recording and the like!