[security-services] Recommendation: SAML elements should be fullyqualified

At various points we have discussed the notion that wherever
SAML elements in a message, they should be fully qualified with using
the SAML namespace. I guess another way of putting this is a recommendation
to avoid use of SAML elements while making some assumption
about the default namespace.
 
Is this stated someplace in core-19? I can't find it but then maybe I
havent looked in the right places for it.
 
- prateek