There is a considerable amount of standards work completed or in progress
in the IETF related to emergency services. Much of this work has to do with how
emergency information is created, transmitted, packaged, etc as part of the
internet infrastructure. Examples are storing location of an IP address as part
of DHCP, creation and transmission of location for an IP enabled phone (VoIP
issues), Emergency Context Resolution with Internet Technologies (ECRIT),
Telephone Number Mapping (ENUM), Session Initiation Protocol (SI)) Location
Conveyance (uses GML), Presence Identity Data Formal - Location Object (uses
GML), Location-to-Service Translation Protocol (LoST - uses GML) and on and
on.
Much of this work began before or during the CAP 1.0 effort. The work of
the IETF in this area is still evolving as they look to geo-enable other facets
of the infrastructure of the internet.
Any one of these internet standards could provide content to generate a CAP
message.
Cheers
Carl