Definition/explanation of messageProfileId?

[Jon Warbrick]

Please could someone explain, or point me to an explanation of, the 
messageProfileId field in idp-audit.log? I can see that the contents are 
URIs that seem to classify the nature of each exchange (SAML1 SSO, SAML 
1 Attribute Query, SAML 2 SSO, etc.), but what are the possible values and 
what to they each actually mean?

Jon.

-- 
Jon Warbrick
Information Systems Development, Computing Service, University of Cambridge