th a sub-picture area that represents the intersection of the sub-picture areas associated with the scalable layers A and B. sub_region_layer_flag| equal to 1 specifies that the syntax elements base_region_layer_id[i] and dynamic_rect_flag[ for the current scalable layer are present in the scalability information SEI message. Rec. ITU-T H.264 (01/2012) sub_region_layer_flag[1 equal to 0 specifies that the syntax elements base_region_layer_id[i] and dynamic_rect_flag[ i ] for the current scalable layer are not present in the scalability information SEI message. When sub_pic_layer_flag[ i ] is equal to 1, sub_region_layer_flag[ shall be equal to 1. roi_division_info_present_flag| i equal to 1 specifies that the layer pictures with dependency_i equal to dependency are divided along slice group map unit boundaries into multiple rectangular regions of interest, referred to as interactive regions of interest (IROIs), and that the IROI division information is explicitly signalled in the scalability information SEI message as specified later in this clause, and that the syntax elements frame_width_in_mbs_minus1[i] and frame_height_in_mbs_minus1[i) for the current scalable layer are present in the scalability information SEI message iroi_division_info_present_flag[ equal to 0 specifies that the IROI division information for the current scalable layer is not present in the scalability information SEI message. When sub_pic_layer_flag[ is equal to 1, roi_division_info_present_flag[ shall be equal to 0. When roi_division_info_present_flag[ ] is equal to 1, the following is specified: (a) When a primary coded VCL NAL unit of the target access unit set has dependency id equal to dependency_ic and contains any macroblock that resides inside a particular IROI, it shall not contain any macroblock that resides outside of the particular IROI. (b) For all access units sets that can be derived from the target access unit set by invoking the sub-bitstream extraction process as specified in clause G.8.8.1 with dIdTarget equal to depende