 to 232 2, inclusive, are reserved for future use by U-T ISO/IEC. Decoders encountering a value of progressive_refinement_ic in the range of 256 to 511, inclusive, or in the range of 231 to 232 - 2, inclusive, shall ignore (remove from the bitstream and discard) it. Rec. ITU-T H.264 (01/2012) D.2.19 Motion-constrained slice group set SEI message semantics NOTE 1 - The syntax of the motion-constrained slice group set SEI message is dependent on the content of the picture parameter set that is active for the primary coded picture associated with the motion-constrained slice group set SEI message. However, the activation of the associated picture parameter set does not occur until the decoding of the first coded slice NAL unit of the primary coded picture. Since the coded slice NAL units of the primary coded picture follow the motion-constrained slice group set SEI message in NAL unit order, it may be necessary for a decoder to store the RBSP containing the motion-constrained slice group set SEI message until determining the parameters of the picture parameter set that will be active for the primary coded picture, and then perform the parsing of the motion-constrained slice group set SEI message. This SEI message indicates that inter prediction over slice group boundaries is constrained as specified below. When present, the message shall only appear where it is associated, as specified in clause 7.4.1.2.3, with an IDR access unit. The target picture set for this SEI message contains all consecutive primary coded pictures in decoding order starting with the associated primary coded IDR picture (inclusive) and ending with the following primary coded IDR picture (exclusive) or with the very last primary coded picture in the bitstream (inclusive) in decoding order when there is no following primary coded IDR picture. The slice group set is a collection of one or more slice groups, identified by the slice_group_id[i] syntax element. When separate_colour_plane_flag is equal to 1, the term "primary coded pictures" represen