© 2009 by Taylor & Francis Group, LLC SIP Handbook: Services, Technologies, and Security An example of a multipart/related document format follows. <?xml version="1.0"?> <list xmlns="urn:ietf:params:xml:ns: uri="sip:my_friends@lists.handbook.com" version="2" fullState="true"> <name language="en">Friend List</name> <resource uri="sip:John@handbook.com"> <name>John Smith</name> <instance id="ewruwoe" state="active" cid="wqe21ew@handbook.com"/> </resource> <resource uri="sip:Erwin@handbook.com"> <name>Erwin Jones</name> <instance id="wergesdfd" state="active" cid="kiuuoui@handbook.com"/> </resource> <resource uri="sip:Edwin@handbook.com"> <name>Edwin</name> <instance id="uyiyi" state="pending"/> </resource> <resource uri="sip:Bill@handbook.com"> <name>Bill Smith</name> <instance id="uyuiy" state="terminated" reason="rejected"/> </resource> </list> The cid attribute is the content-ID for the corresponding section in the multipart body. The cid attribute refers only to top-level parts of the multi- part/related document for which the RLMI document in which it appears is the root. We consider a multipart/related document containing three parts; we'll label these parts A, B, and C. Part A is type "application/rlmi+xml," part B is type multipart/related, and part C is type "application/pidf+xml." Part B is in turn a document containing three parts: D, E, and F. Part D is of type "application/rlmi+xml," and parts E and F are of type "application/ pidf+xml." Any cid attributes in document A must refer only to parts B or C. Referring to parts D,E, or F would be illegal. Similarly, Any cid attributes in document D must refer only to parts E or F. Referring to any other parts would be illegal. Top Level Document: multipart/related Part A: application/rlmi+xml Part B: multipart/related C 2009 by Taylor & Francis Group, LLC SIP Event Notification and Presence Information Part D: application/rlmi+xml Part E: application/pidf+xml Part F : application/pidf+xml Part C: application/pidf+xml 5.5.5 A Walk-Through Example This section 