Hello happy people of the TMS forum!
Perhaps I should clarify, as I "conceived" the page!
For an "In Service" tram, it should NOT be in the workshop (EXCEPT when it is be checked for service or the frequent checks), and operable at the drop of a hat.
For a "Out of Service" tram, it should be either currently in the works (such as 1297/106), or in the depot about to receive works (166). Trams under restoration should not be out of service
Trams "on Display" are either inoperable, unrestored, or have some other fault preventing them from being temporarily out of service. Trams such as 1282 (I belive this has been out of service for a few years now), 35, 1 (all the 1s) etc fall into this.
The others, such as Works Car, In Store, Under Restoration etc should be pretty straight forward!
Oh, and may I just mention a better and more up-to-date version, complete with FactFiles on some of the cars, is available at
http://train.spottingworld.com/National%20Tramway%20Museum!
Thanks,
BG7