This object controls if RTCPXR
(Real Time Control Protocol Extended Report) is enabled.
If this object is set to 'true', both transmission and
reception of RTCPXR packets are enabled; otherwise,
transmission of RTCPXR packets is disabled while any
received RTCPXR packets are ignored.
If object cdspVqmControl is set to 'xnq (3)', this
object is read-only with the value of 'true'.