Psssst, "typing" is a valid command.
But only in Pchat, I think. In game people used /afk but I think there was something that caused issues using it in Pchat so CW invented /typing. Now mind you, everything I just said is from memory, except checking the wiki for the /typing command, so take it with a grain of salt.
And she's right, your version is way old. It's probably not recognizing the typing command because it wasn't invented back when .99d was relevant.