A Session Initiation Protocol (SIP) Event Package and Data Format for Various Settings in Support for the Push-to-Talk over Cellular (PoC) Service
draft-garcia-sipping-poc-isb-am-04

From Joel Halpern (Gen-ART review):

As a minor question, the document definition (both the description and the schema) permit a document with no entity elements.  This causes me to wonder why this is permitted, when it would occur, and what a receiver should do with such a document?

  Section 5.7 says:
  >
  > It is RECOMMENDED that the signature be by an authority over the
  > domain of the user.
  >
  I suggest:
  >
  > The NOTIFY SHOULD be signed by an authority over the domain of
  > the user. 

  Section 5.7 says that the NOTIFY ought to be signed by "an authority
  over the domain of the user."  What in the certificate of the signer
  indicates that they are an authority over the domain?  This is not
  a DISCUSS comment because RFC 3856 includes the same problem.  I
  believe that the working group needs to address this problem.  Without
  an answer to this question, ad-hoc mechanisms will be developed to
  determine whether or not a particular certificate is associated with
  "an authority over the domain of the user."