to the Main profile shall obey the following constraints: Only I, P, and B slice types may be present. NAL unit streams shall not contain nal_unit_type values in the range of 2 to 4, inclusive. Arbitrary slice order is not allowed. The syntax elements chroma_format_idc, bit_depth_luma_minus8 bit_depth_chroma_minus8, apprime_y_zero_transform_bypass_flag, and seq_scaling_matrix_present_flag shall not be present in sequence parameter sets. Picture parameter sets shall have num_slice_groups_minus1 equal to 0 only. Picture parameter sets shall have redundant_pic_cnt_present_flag equal to 0 only. syntax elements transform_8x8_mode_flag pic_scaling_matrix_present_flag, second_chroma_qp_index_offset shall not be present in picture parameter sets. The syntax element level prefix shall not be greater than 15 (when present). The syntax elements pcm_sample_luma[i] with i = 0..255, and pcm_sample_chroma[i] with i =0..2 * MbWidthC * MbHeightC - 1, shall not be equal to 0 (when present). The level constraints specified for the Main profile in clause A.3 shall be fulfilled. Conformance of a bitstream to the Main profile is indicated by profile_ide being equal to 77. Decoders conforming to the Main profile at a specified level shall be capable of decoding all bitstreams in which profile_idc is equal to 77 or constraint_set1_flag is equal to 1 and in which level ide and constraint_set3_flag represent a level less than or equal to the specified level. A.2.3 Extended profile Bitstreams conforming to the Extended profile shall obey the following constraints: Sequence parameter sets shall have direct_8x8_inference_flagequal to 1. The syntax elements chroma_format_idc, bit_depth luma minus8, bit depth_chroma_minus8, qpprime_y_zero_transform_bypass_flag and seq_scaling_matrix_present_flag shall not be present in sequence parameter sets. Picture parameter sets shall have entropy_coding_mode_flag equal to 0. Picture parameter sets shall have num_slice_groups_minus1 in the range of 0 to 7, inclusive. Rec. ITU-T H.264 (01/2012) syntax eleme