[Zope] Guru Meditations on roles, __roles__ etc?

[John Ziniti]

Would someone in the know care to give a brief introduction
to the way in which available roles are presented in the
"Security" tab of items which inherit from SecurityManager.

I would like the roles available to be culled from our LDAP
database (via a LDAPLoginAdapter).

Is acl_users automatically asked for any roles it has?  Or is
this the responsibility of the containing folder/product?

Thanks in advance for any advice,

John Ziniti