[FS_DCE_MED] Key Issue Description for Interworking with MTSI
Observation 1) In TS 23.228, IMS AS modifies the endpoint type of the application data channel from P2P to P2A to support IMS DC interworking via DC AS.
Observation 2) SDP answerer for the application DC shall not change the value of endpoint parameter in "a=3gpp-req-app" attribute.
Observation 3) DC application in the originating DCMTSI UE is required to identify the interworking mode is enabled to distinguish the actual target endpoint for a specific media flow.