gid number in posix account!

[magobin at gmail.com (Alex aka Magobin)]

> No, I think it has to be a number.

> Right.  It's on our wishlist - I don't know when we'll get around to it.
> http://directory.fedora.redhat.com/wiki/Wishlist


uhm, so can you confirm me that to create a new account I have to
specify uid and gid in numerical way ?
And in this way if mail is 4 example 501 any user with gid 501 is member
of mail group?

thanks
Alex