6. RFC4871 Section 2.9 Signing Domain Identifier (SDID)
...
A single domain name -> A single, registered domain name
...
7. RFC4871 Section 2.10 Agent or User Identifier (AUID)
...
A single domain name -> A single, syntactically valid domain name
Well, to make them similar, how about this for 7?:
A single domain name -> A single domain name, not necessarily registered,
Barry
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