[Mobhack]

If the OP is talking about the formation lettering - the 5 key toggles that IIRC. Search the Game Manual under the "CD Extended features" section for the section titled "Show/Hide Formation ID's".

Formation IDs <> ID tags
Formation ID == B08 etc text (controlled bythe 5 key)
ID tags == miniature national flags (controlled with the preferences menu)

There is also a setting for IDs in the misc section of the game launcher - that shows Mobhack line numbers for units and formations in the purchase screen - its for error reporting/debugging purposes.