There are lists of tags contained in datasets within TOPS (a dataset is where TOPS is being used as a rudimentary text editor, basically a sort of "readme" file within TOPS from the days before any other sort of text editor, word processor or the ability to email documents would have been available in a TOPS office). The tags in the datasets would match up with the actual TOPS "tagging tables" that controlled the routing instructions explained in the posts above. The tags in these datasets represent a snapshot of their use around 20 years ago, although plenty of the tags listed would have been long out of use even then. The dates shown underneath each geographical group of tags show when the datasets were last updated in the early 2000s. It's possible that the tagging tables were subsequently updated without the datasets being revised, but given the rapid decline of wagonload traffic over the subsequent few years, and that tags were already basically obsolete by 2010, these can be considered to show the current meaning of a tag. This also means that tags shown in the datasets do not necessarily match up with their earlier use, so tags that existed for places like Wath Yard or Mansfield Coal Concentration depot have either been deleted from the dataset entirely or could potentially have been reused.
While the lists of tags are useful to understand the current meaning of each tag, the actual routing instructions a tag gives will not make sense today as they are still based around the "Enterprise" wagonload network that no longer exists. The only vaguely comparable wagonload network still in existence is the network of infrastructure trips (using many former Speedlink yards), but the present methods of routing wagons on this are the daily "network wires" - an email to the yards (local distribution centres) telling them what traffic needs to go on each train. The difference here is that Network Rail can centrally control everything because they are also the customer generating the traffic, whereas Speedlink had to be set up to deal with traffic originating from a variety of sources on a daily basis that was not completely predictable in advance, and the sheer volume of traffic would have made it unrealistic to manually micro-manage every wagon's routing on every service to every yard on a daily basis.
In the attached text file I've combined the list of tags with another dataset which contains a document titled "General Principles of Tagging." That document must have been written even earlier - it gives the Stanox for Fryston colliery as an example and was written by British Rail HQ at Paddington!
For those who are understandably wary of downloading any files found online (or simply not logged in) I'll start a thread in the nostalgia section and paste in sections of the tag codes in instalments, and see if the tags trigger any memories of their use "back in the day."
As already mentioned, the tagging system is obsolete and the information here is mainly of historical interest, so if anyone wants to reproduce or use the information elsewhere feel free. I've added a paragraph of explanatory text before the list of TOPS tags (which is in lowercase, unlike the rest of the text) but the rest is copied from the original TOPS datasets.
For general context, the tags represent routing instructions to locations and are not the code for the location itself. For example "Warrington trunk tag" for 60mph traffic is 352, but the actual location number (Stanox) for Warrington Arpley is 35550 - note the first two digits of the tag match the Stanox, as explained in the "General Principles of Tagging." The Stanox numbers for TOPS locations generally follow a logical geographical sequence, for example Thurso station is 01001 and Dollands Moor Yard is 89735.
Stanox codes are listed on the railwaycodes website, although it doesn't always have the data for historical locations that no longer exist, and some obsolete Stanoxes have been reused over the years:
http://www.railwaycodes.org.uk/crs/crs0.shtm
Theres' a handy guide to the general geographical spread of Stanox codes here:
https://wiki.openraildata.com/index.php/STANOX_Areas
You can also see the same geographical progression in the list of tags, given that the first two digits follow the Stanox.