3.  The Receiving Server SHOULD send a stream header back to the
       Originating Server, including a unique ID for this interaction:

       -- SHOULD?  how would it work considering later steps?  Should be "MUST"


If the server receives an IQ stanza of type "get" or
   "set" with no 'to' attribute and it understands the namespace that
   qualifies the content of the stanza, it MUST either process the
   stanza on behalf of the sending entity (where the meaning of
   "process" is determined by the semantics of the qualifying namespace)
   or return an error to the sending entity.

             --- word order:
                     if (IQ AND (get OR set) AND "no to" AND understand)
                  vs
                     if (IQ AND (get OR set) AND "no to") {
                         if (understand) { process; }
                         else { error; }
                     }