/etc/citadel/messages/mainmenu is in citadel-server 8.24-1+b3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Room cmds: <K>nown rooms, <G>oto next room, <.G>oto a specific room,
<S>kip this room, <A>bandon this room, <Z>ap this room,
<U>ngoto (move back)
Message cmds: <N>ew msgs, <F>orward read, <R>everse read, <O>ld msgs,
<L>ast five msgs, <E>nter a message
General cmds: <?> help, <T>erminate, <C>hat, <W>ho is online
Misc: <X> toggle eXpert mode, <D>irectory
(Type .Help SUMMARY for extended commands, <X> to hide this menu)
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