ITU-T ISO/IEC. These values shall not be used in bitstreams conforming to this Recommendation International Standard, but may be used in future extensions of this Recommendation International Standard by ITU-T ISO/IEC. 3.131 residual: The decoded difference between a prediction of a sample or data element and its decoded value. 3.132 run: A number of consecutive data elements represented in the decoding process. In one context, the number of zero-valued transform coefficient levels preceding a non-zero transform coefficient level in the list of transform coefficient levels generated by a zig-zag scan or a field scan. In other contexts, run refers to a number of macroblocks. Rec. ITU-T H.264 (01/2012) 3.133 sample aspect ratio: Specifies, for assisting the display process, which is not specified in this Recommendation International Standard, the ratio between the intended horizontal distance between the columns and the intended vertical distance between the rows of the luma sample array in a frame. Sample aspect ratio is expressed as h:v, where h is horizontal width and V is vertical height (in arbitrary units of spatial distance). 3.134 scaling: The process of multiplying transform coefficient levels by a factor, resulting in transform coefficients. 3.135 sequence parameter set: A syntax structure containing syntax elements that apply to zero or more entire coded video sequences as determined by the content of a seq_parameter_set_id syntax element found in the picture parameter set referred to by the pic_parameter_set_id.s syntax element found in each slice header. 3.136 shall: A term used to express mandatory requirements for conformance to this Recommendation International Standard. When used to express a mandatory constraint on the values of syntax elements or on the results obtained by operation of the specified decoding process, it is the responsibility of the encoder to ensure that the constraint is fulfilled. When used in reference to operations performed by the decoding process, any decoding process that 