Creating new roles

[Steve Brueckner]

I'm just getting started with SELinux.  I've read a bunch and just installed
FC3.  

I'm trying to add a new role, but can't figure out where roles are defined.
The O'Reilly book says they're "scattered around the policy tree" and Debian
references say they're in users.te, which doesn't appear to exist in FC3.

If I can find where the few extant roles are defined, I can probably figure
out how to define my own.  Or should I be trying to do it from scratch by
making a new file?  In which case I could use some hints on how to do it.

 - Steve