ccess units with temporal id equal to sei_temporal_id[i ] may or may not be present in the target access unit set. When access units with temporal id equal to ei_temporal_id| are not present in the target access unit set, the i-th bitstream subset is considered as not existing. When access units with temporal_id equal to sei_temporal_id[i] are present in the target access unit set, the i-th bitstream subset is the bitstream subset that is obtained by invoking the bitstream extraction process as specified in clause G.8.8.1 for the target access unit set with tIdTarget equal to sei_temporal_id[i dIdTarget equal to 0, and qIdTarget equal to 0 as the inputs. sei_timing_info_present_flag[ equal to 1 specifies that sei_num_units_in_tick[i], sei i], and sei_fixed_frame_rate_flag[i are present in the base layer temporal HRD SEI message. sei_timing_info_present_flag[i) equal to 0 specifies that sei_num_units_in_tick[i], sei_time_scale[i] and sei_fixed_frame_rate_flag[ i are not present in the base layer temporal HRD SEI message. The following syntax elements for the i-th bitstream subset are specified using references to Annex E. For these syntax elements the same semantics and constraints as the ones specified in Annex E apply, as if these syntax elements sei_num_units_in_tick[i], sei_time_scale[i], sei_fixed_frame_rate_flag[ ], sei_nal_hrd_parameters_present_flag[i] arameters_present_flag i], sei_low_delay_hrd_flag[i andsei_pic_struct_present_flag[i]were present num_units_in_tick, time_scale, ixed_frame_rate_flag, nal_hrd_parameters_present_flag, 1 hrd parameters_present_flag low_delay_hrd_flag and pic_struct_present_flag respectively, in the VUI parameters of the active SVC sequence parameter sets for the i-th bitstream subset. The parameters for the i-th bitstream subset that are coded in the base layer temporal HRD SEI message shall be correct, as if these parameters are used for conformance checking (as specified in Annex C) of the i-th bitstream subset. sei_num_units_in_tick| i ] indicates the value of num_units_in