Systems and methods are provided which allow receivers to recover the decoding order of network abstraction layer (NAL) units conveyed in different Real Time Protocol (RTP) sessions. An indication of decoding order for application data units (ADUs) in each packet is included in the packet structure of a PACSI NAL unit, when the PACSI NAL unit is a single-time aggregation packet type A (STAP-A) packet and the PACSI NAL unit is the first NAL unit in an aggregation packet (e.g., when a receiver is subscribed to different RTP session that convey NAL units). If the receiver is subscribed to only a base layer RTP session, the CL-DON indication can be ignored.