Authn context help

Folks,

As you may recall, Giles Hogben of the European Network and Information
Security Agency is working on developing an assurance scheme leveraging SAML
2 authentication context.

Apparently they've run into some difficulties understanding parts of the
existing authn context work.  Specifically he says, "The problem we are
having is that there does not seem to be an adequate explanation anywhere of
some of the items within the Authentication context schema (e.g.
TechnicalProtectionBaseType element). The only document I can find which
might have an explanation is here:
http://docs.oasis-open.org/security/saml/v2.0/saml-authn-context-2.0-os.pdf
. Also in creating new context classes, we have some trouble understanding
why elements have been included in the existing classes. It would be great
if we could talk to someone briefly on the phone just to get us over these
hurdles..."

Unfortunately I was not with the TC when the authn context stuff was
originally developed nor have I done much with it - so I can't be of much
help.  Would one of the more tenured members of the TC be willing to provide
Giles with some assistance/advice?

Thanks,
Brian