>What are the "extra" fields like iusergroups and iuserpreferences and iusers used for?
>Where are they updated from?
>What are valid values?

Strangely, after replying to John in a prior thread, I went looking through the code for just this thing. Code References has no hits outside of the table fieldnames themselves.

If I had to hazard a guess, it was intended to control menu entries for the developer tools, then dropped in favor of a more sane method of security.

Chris