I would appreciate clarification on the following with respect to the
Receipt Request attribute:
1. May a CounterSignature contain a receipt request?
2. If so, MUST all receipt requests in a SignedData be identical? The
spec specifies that all Receipt Requests be identical. Is it the intent
that CounterSignatures containing a receipt request MUST also be identical
with other receipt requests if it exists? I don't see why each
countersignature can not have a different receipt request.