Locomotives and units usually have a short space between the class number and the serial number in the numbers physically applied to their fronts and/or sides. Some published references also feature this (For example, 47 401). To (hopefully) avoid any confusion, all numbers on this website are shown without spaces.

RIV/UIC/European Vehicle Numbers are shown with a period between each section, and a hyphen before the check digit. For example, 37.70.6955.101-2. The hyphen is carried on the vehicles but the sections of the numbers are usually separated by spaces rather than periods. The sorting is by country code, then by type code, then by serial and finally by exchange code. So, for example, 37.70.6955.100-2 would come after 33.70.6955.100-6 but before 33.70.6955.101-4.

Re-used numbers are indicated by a figure in brackets after the number. For example, 37274 (2) was the second locomotive to carry the number 37274. If a vehicle reverts to a number it had previously carried, this is shown by the letter R, for example 37308 (R) was a locomotive that carried number 37308, then carried something else, then reverted to 37308. If a vehicle reverts to a given number more than once, this would be shown by R2, R3 etc, as in 37165 (R2), where the history is D6865 - 37165 - 37374 - 37165 (R) - 37374 (R) - 37165 (R2). Similarly, 2R etc would be used to show an instance of a vehicle carrying a reused number reverting to that number. For example, 2001 (5R) was a Southern Region multiple unit that was the fifth such to carry the number 2001. Originally 3001 (2), it became 2001 (5), then 2901, then 2001 (5R).

Instances of a vehicle being allocated an additional number (such as the MXA wagons that were given numbers in the 82.70.4703.001-217 series in addition to their original 95xxxx numbers) are indicated by (+) after the number, as in 82.70.4703.001-6 (+). In cases where a vehicle was given two numbers at the same time (as with many recent track machines), the number in the more familiar series is treated as the main number and the other number (usually a European Vehicle Number) gets a (+) indicator. In terms of this website, if you see a (+) after a number it will generally mean that notes, sightings, photos etc will be logged against the other ('primary') number.

Known instances of an allocated number not being carried are indicated by a letter n in brackets, as in 042193 (n). In a few cases (generally restricted to static internal user vehicles) this was where a vehicle carried no number externally. Most cases are those where the vehicle was officially re-numbered but the new number was not physically applied before the vehicle was withdrawn.

Changes of stock number after the vehicle's main-line career (such as in industrial use or preservation) are mainly ignored in the database, but they may be referenced in notes. Information about the subsequent life of a given vehicle will normally be linked to its last main-line number. For example, loco D4 is preserved as such but any items relating to it should be logged against the number 44004 (its final number whilst on the main-line).

The distinction between Pre-TOPS and TOPS set numbers for EMUs is not generally made. For example, the first Glasgow 'Blue Train' was numbered 001 from 1959 until 1979, when it became 303001. For convenience, this website treats this as the same number and lists information under 303001. This applies to all types that were allocated a TOPS class, even those where the units were withdrawn before the full numbers were applied (for example, class 306). Hugh Longworth's epic study of BR EMUs does provide details of the changes from 'short' to 'long numbers', with dates.

The numbers of the High Speed Train power cars (43000 to 43198) were originally considered to be coaching stock numbers, but later changed to be in the locomotive series. All references on this site are shown under the loco series (even though 43000 is not a 'legal' locomotive number!).

BR-built Fish Vans were originally classified as coaching stock, and are referenced as such on this website. Although many were converted to Special Parcels Vans, the whole class seems to have been later reclassified as freight stock, though erroneously still retaining their coaching stock regional allocation prefixes (eg E87560). This got more complicated when examples were transferred to departmental use. Coaching stock transferred was normally given a new number, but the fish vans were dealt with in the same way as wagons, i.e. by just adding a D prefix. For example, W87674 became DW87674.

TOPS sub-classes for locomotives were introduced in 1969 but were revised in 1973 to match the loco numbers. For example, steam-heat 47s were initially classified as 47/1 but when the locos were given TOPS numbers starting at 47001, the classification was changed to 47/0. On this website the interim sub-classes are generally ignored (Although I may have included some early EMU codes which were shortlived. This will be reviewed...).

The normal method of showing TOPS sub-classes is used, namely a slash between the class number and the sub-class indicator. For example, 37/4 and 165/1.

Details such as listings and photos are normally linked to a TOPS sub-code (e.g. 47/3) rather than the 'short' code (e.g. 47). For loco classes that only had one variant, the sub-code was not in common use. For example, 'Deltic' locos were always referred to as class 55, and never class 55/0. However, there are a couple of reasons for doing this. Firstly, the sub-code did technically exist. The design code for class 55 locos was 55-0AX, indicating that they belonged to sub-class 55/0. Secondly, is simplifies matters if a second sub-class is later introduced. To illustrate, all class 08s and class 50s were in a single class for many years. When sub-classes 08/9 and 50/1 were later introduced, the 'base' classes became 08/0 and 50/0 respectively.

Most wagon types are assigned a four-letter TOPS code, although it is normal for just the first three letters to be carried on the wagon. On the TOPS computer system, these codes are shown as one continuous code (e.g. FGAF), but on this site the normal practice of inserting a hyphen is used (e.g. FGA-F).

Where a TOPS class, sub-class or code has been used more than once (for different purposes), the second (and any later) uses are indicated by a number in brackets after the class. For example, class 141 was until 1979 used for Cravens driving trailers. From 1984 it was applied to BR/Leyland railbuses, these being shown on this website as class 141 (2). The initial use of class 141 did not have subclasses, so the later 141/0 and 141/1 are shown without a number in brackets, even though they are subclasses of 141 (2).

Before the advent of TOPS, technical details of rolling stock were shown on diagrams. These were referenced by their page number within a diagram book. All coaching stock (including those in multiple units) appeared in a single book, so diagram numbers are shown on their own and without leading zeros. For example, the diagram on page 10 of the carriage diagram book was a Sleeper Second, and would be referred to as diagram 10. With wagons, there were separate books to cover normal wagons and specially constructed wagons (and further books for containers and private-owner wagons). The same page number could appear in two or more books. To avoid confusion, the standard method of referencing the book number, followed by a slash, followed by the page number is used. For example, 1/250 is page 250 (a Ventilated Meat Van) in book 1, 2/250 is page 250 (a Lowmac MU) in book 2 and 3/250 is page 250 (an AF-type container) in book 3. For page numbers below 100, leading zeros are added to make the number up to three characters, as in 1/007.

Prior to 1955 there were three classes of passenger accommodation on BR trains, of which Second Class was by far the rarest. Second Class was abolished in 1955 and what was Third Class became the new Second Class. Coach designations and type codes were also changed, such as Corridor Third/TK becoming Corridor Second/SK. For convenience, on this website most references to Third Class have Second Class substituted. For example, a coach may be shown as being built as an SK, even though it may have originally been classified as a TK. Exceptions are made for stock that was withdrawn before 1955.

Since the codes assigned to them were liable to change, references to loco sheds and depots are made using their full names. For example, Tinsley shed was 43A then became TI under TOPS, though the TI code was later re-used for Temple Mills.

Dates are generally shown in UK format, whereby 01/02/2003 is 1st February 2003. Some date fields are actually set to text format, so as to allow imprecise entries (such as 'circa March 2020') but still allow sorting. Entries in these fields are set out as dYYYYMMDDq, where d is the letter d (not the day!), YYYY is the 4-digit year, MM is the 2-digit month (where known), DD is the 2-digit day (where known) and q is any qualifier such as 'by', 'circa', 'not before' or 'period ending'. For example, d201512b indicates 'by December 2015'. I hope to have provided decoding for all instances where such dates could appear, but there may be the odd few remaining.