er set RBSP (as the active picture parameter set RBSP). In this case, the contents of the de-activated and activated SVC sequence parameter set RBSP are mutually restricted as described below. Hence, within a coded video sequence, multiple successively activated/de-activated SVC sequence parameter set RBSPs can be present. For the following specification in this clause, the activating layer buffering period SEI message for a particular value of DQId is specified as follows: If the access unit contains a buffering period SEI messages that is included in a scalable nesting SEI message and is associated with the particular value of DQId, this buffering period SEI message is the activating layer buffering period SEI message for the particular value of DQId. Rec. ITU-T H.264 (01/2012) Otherwise, if the particular value of DQId is equal to 0 and the access unit contains a buffering period SEI message that is not included in a scalable nesting SEI message, this buffering period SEI message is the activating layer buffering period SEI message for the particular value of DQId. Otherwise, the access unit does not contain an activating layer buffering period SEI message for the particular value of DQId. When a sequence parameter set RBSP (nal_unit_type is equal to 7) with a particular value of seq_parameter_set_id is not already the active layer SVC sequence parameter set RBSP for DQId equal to 0 and it is referred to by activation of a picture parameter set RBSP (using that value of and the picture parameter set RBSP is activated by a coded slice NAL unit with equal to 1 or 5 and DQIdMax is greater than 0 (the picture parameter set RBSP becomes the active layer picture parameter set RBSP for DQId equal to 0) and the access unit does not contain an activating layer buffering period SEI message for DQId equal to 0, the sequence parameter set RBSP is activated for layer representations with DQId equal to 0. This sequence parameter set RBSP is called the active layer SVC sequence parameter set RBSP for DQId equal to 0 until it