Zsh completion configuration

[joe M <joe9mail@xxxxxxxxx>]

Hello,

I am trying to figure out how to add "history-words" as a group within
_complete, similar to aliases or functions.

I see that the file Completion/Zsh/Type/_command_names adds the
different tags using compadd -k.

But, I could not figure out what compadd does from the zsh source. Any
thoughts on what compadd does, or, how I can add another tag to the
list of tags suggested by _command_names?

Thanks
Joe