Thank you. This confirms a sneaking suspicion I had.
However, there is one thing I can't work out: the new 'vassal' entries in Civ4DiplomacyInfos point to text in Civ4DiplomacyText.xml (or Civ4GameText_Warlords_Diplomacy.xml), but there is no corresponding text in those files.
So patching my 'Infos.xml would make absolutely no difference. Because Firaxis never made corresponding entries in the text files themselves.
Right?
I could of course fix that. But as it currently stands, as far as I can work out, no one gets vassal related diplomacy text -- ever. Even playing without mods.
Or what am I missing?
EDIT: Well, I've discovered what I'm missing. Those entries are for no good reason hidden inside CIV4GameText_Warlords.xml. So I guess I'll be uploading a patch of sorts now...