future use by ITU-T | ISO/IEC. Decoders encountering a value of pan_scan_rect_id in the range of 256 to 511 or in the range of 231 to 232 2 shall ignore (remove from the bitstream and discard) it. pan_scan_rect_cancel_flag equal to 1 indicates that the SEI message cancels the persistence of any previous pan-scan rectangle SEI message in output order. pan_scan_rect_cancel_flag equal to 0 indicates that pan-scan rectangle information follows. pan_scan_ent_minusl specifies the number of pan-scan rectangles that are present in the SEI message. pan_scan_ent_minusl shall be in the range of 0 to 2, inclusive. pan_scan_cnt_minusl equal to 0 indicates that a single pan-scan rectangle is present that applies to all fields of the decoded picture. pan_scan_cnt_minusl shall be equal to 0 when the current picture is a field. pan_scan_cnt_minusl equal to 1 indicates that two pan-scan rectangles are present, the first of which applies to the first field of the picture in output order and the second of which applies to the second field of the picture in output order. pan_scan_ent_minusl equal to 2 indicates that three pan-scan rectangles are present, the first of which applies to the first field of the picture in output order, the second of which applies to the second field of the picture in output order, and the third of which applies to a repetition of the first field as a third field in output order. pan_scan_rect_left_offset[i], pan_scan_rect_right_offset[i, pan_scan_rect_top_offset[i] pan_scan_rect_bottom_offset[ specify, as signed integer quantities in units of one-sixteenth sample spacing relative Rec. ITU-T H.264 (01/2012) to the luma sampling grid, the location of the pan-scan rectangle. The values of each of these four syntax elements shall be in the range of -231 + 1 to 231 - 1, inclusive. The pan-scan rectangle is specified, in units of one-sixteenth sample spacing relative to a luma frame sampling grid, as region frame horizontal coordinates 16*CropUnitX * frame_crop_left_offset + pan_scan_rect_left_offset[i 16 * 16 