source of audience value?

[ksully-execute]

using the simple password tutorial, when I do an authentication, it works, but I get back a uuid value for aud (audience) that I don't recognize. It's not the client id, nor the users id. Where is this value coming from?
And you're supposed to be able to add additional audiences in the client definition, but I don't see where in the TUI client. Can you point me in the right direction?