e additional trailing_zero_8bits syntax elements. When it is the first byte stream NAL unit in the bitstream, it may also contain one or more additional leading_zero_8bits syntax elements. Byte stream NAL unit syntax and semantics B.1.1 Byte stream NAL unit syntax byte_stream_nal_unit(NumBytesInNALunit) { Descriptor while( next_bits(24) != 0x000001 && next bits( 32) !=0x00000001 leading_zero_8bits /* equal to 0x00 */ if( next_bits(24)!=0x000001) zero_byte/*equalto 0x00* start_code_prefix_one_3bytes 1* equal to 0x000001 */ f(24) nal_unit( NumBytesInNALunit) while( more_data_in_byte_stream()& next_bits(24)!=0x000001 && next_bits(32)!=0x00000001) trailing_zero_8bits /*equal to 0x00 B.1.2 Byte stream NAL unit semantics The order of byte stream NAL units in the byte stream shall follow the decoding order of the NAL units contained in the byte stream NAL units (see clause 7.4.1.2). The content of each byte stream NAL unit is associated with the same access unit as the NAL unit contained in the byte stream NAL unit (see clause 7.4.1.2.3). leading_zero_8bits is a byte equal to 0x00. NOTE - The leading_zero_8bits syntax element can only be present in the first byte stream NAL unit of the bitstream, because (as shown in the syntax diagram of clause B.1.1) any bytes equal to 0x00 that follow a NAL unit syntax structure and precede the four-byte sequence 0x00000001 (which is to be interpreted as a zero_byte followed by a start_code_prefix_one_3bytes) will be considered to be trailing_zero_8bit syntax elements that are part of the preceding byte stream NAL unit. zero_byte is a single byte equal to 0x00. When any of the following conditions are true, the zero_byte syntax element shall be present: the nal_unit_type within the nal_unit() is equal to 7 (sequence parameter set) or 8 (picture parameter set), the byte stream NAL unit syntax structure contains the first NAL unit of an access unit in decoding order, as specified in clause 7.4.1.2.3. start_code_prefix_one_3bytes is a fixed-value sequence of 3 bytes equal to 0x000001. T