spsA is the active SVC sequence parameter set RBSP for an IDR access unit and spsB is the active SVC sequence parameter set RBSP for any non-IDR access unit of the same coded video sequence. The SVC sequence parameter set RBSPs spsA and spsB are restricted with regards to their contents as specified in the following. The values of the syntax elements in the seq_parameter_set_data() syntax structure of spsA and spsB may only differ for the following syntax elements and shall be the same otherwise: profile_idc, constraint_setX_flag (with X being equal to 0 to 5, inclusive), reserved_zero_2bits, level_idc,seq_parameter_set_id,timing_info_present_flag, num_units_in_tick, time_scale, fixed_frame_rate_flag, nal_hrd_parameters_present_flag, cl_hrd_parameters_present_flag low_delay_hrd_flag, pic_struct_present_flag, and the hrd_parameters() syntax structures. When spsA is the active SVC sequence parameter set RBSP and spsB is the SVC sequence parameter set RBSP that is referred to by the coded slice NAL units of the layer representation with DQId equal to DQIdMax, the level specified by level and constraint_set3_flag) in spsA shall not be less than the level specified by level_idc (or level_idc and constraint_set3_flag) in spsB. When the seq_parameter_set_svc_extension() syntax structure is present in both spsA and spsB, the values of all syntax elements in the seq_parameter_set_svc_extension() syntax structure shall be the same. It is a requirement of bitstream conformance that the following constraints are obeyed: For each particular value of DQId, all coded slice NAL units of a coded video sequence shall refer to the same value of seq_parameter_set_id (via the picture parameter set RBSP that is referred to by the value of pic_parameter_set_ The value of seq parameter in a buffering period SEI message that is not included in a scalable nesting SEI message shall be identical to the value of seq_parameter_set_id in the picture parameter set RBSP that is referred to by coded slice NAL units with nal_unit_type equal to 1 o