The sdp_add_zone() function adds the ZONE (z=) SDP field to the session structure that is specified by the value of the session parameter (sdp_session_t) using the time and offset parameters. You can add multiple time and offset values for a single zone field by calling this function for each time/offset value pair.
Return Values: The sdp_add_zone() function returns 0 when the function completes successfully. When mandatory parameters are not present, the function returns EINVAL. When memory allocation fails, the function returns ENOMEM. The value of errno does not change in the event of an error.