 the samples from the region of the bottom field of the frame that lie within the spatial region of the macroblock pair. For a frame macroblock pair, the bottom macroblock represents the samples of the frame that lie within the bottom half of the spatial region of the macroblock pair. broken link: A location in a bitstream at which it is indicated that some subsequent pictures in decoding order may contain serious visual artefacts due to unspecified operations performed in the generation of the bitstream. byte: A sequence of 8 bits, written and read with the most significant bit on the left and the least significant bit on the right. When represented in a sequence of data bits, the most significant bit of a byte is first. byte-aligned: A position in a bitstream is byte-aligned when the position is an integer multiple of 8 bits from the position of the first bit in the bitstream. A bit or byte or syntax element is said to be byte-aligned when the position at which it appears in a bitstream is byte-aligned. byte stream: An encapsulation of a NAL unit stream containing start code prefixes and NAL units as specified in Annex B. can: A term used to refer to behaviour that is allowed, but not necessarily required. Rec. ITU-T H.264 (01/2012) category: A number associated with each syntax element. The category is used to specify the allocation of syntax elements to NAL units for slice data partitioning. It may also be used in a manner determined by the application to refer to classes of syntax elements in a manner not specified in this Recommendation International Standard. chroma: An adjective specifying that a sample array or single sample is representing one of the two colour difference signals related to the primary colours. The symbols used for a chroma array or sample are Cb and NOTE - The term chroma is used rather than the term chrominance in order to avoid the implication of the use of linear light transfer characteristics that is often associated with the term chrominance. coded field: A coded representation of