can a service determine user identity without validating a service ticket?

[Dom]

Hi Andrew,

That's a great question. Great documentation, something that everyone
understands, can be hard to achieve. Personally, I try not to use acronyms in
help documents, even for long winded objects like Ticket Granting Ticket. Some
standard diagrams might also be useful, a UML sequence diagram, or even a
classic flow diagram. If I can help please let me know. 
Thanks to you and Scott for your time in answering my questions.
Regards,
Dom