In order to access the specified resource the device has to join the multicast group provided by the mcast-addr and port and optional src-host in the URI. It compares all the parameters provided in the query component of the URI against the corresponding DVBSTP protocol fields and extracts all the segments that match. The parameters in the query component of the URI are optional. In case a parameter is not provided the corresponding field in the DVBSTP protocol will not be used for the comparison. In case a Download Session ID is provided in the fragment component of the URI, the device has to search all the extracted segments for the session description with the specific Download Session ID. G.3.3 DVB-MCAST URI scheme for SAP The basic DVB-MCAST URI scheme defined in clause G.3.1 is extended in order to reference SDP data provided via the SAP protocol. The PT is set to 'sap'. No further information has to be provided in the query part of the URI as no further payload identification is provided by SAP. In order to reference a specific session description within the SDP information the CDS Download Session ID can be provided within the fragment part of the URI. The fragment syntax is not specific to the SAP delivery but to the delivered media, the SDP session description in this case. The DVB-MCAST URI scheme for SAP is:
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