ame. Each row of a layer bottom field is spatially located immediately below a corresponding row of a layer top field. G.3.25 layer field: An assembly of alternate rows of a layer frame. A layer frame is composed of two layer fields, a layer top field and a layer bottom field. G.3.26 layer frame: A layer frame contains an array of luma samples that represents an intermediate decoding result for a field or a frame in monochrome format or an array of luma samples and two corresponding arrays of chroma samples that represent an intermediate decoding result for a field or a frame in 4:2:0, 4:2:2, and 4:4:4 colour format. A layer frame consists of two layer fields, a layer top field and a layer bottom field. G.3.27 layer picture: A collective term for a layer field or a layer frame. G.3.28 layer top field: One of two layer fields that comprise a layer frame. Each row of a layer top field is spatially located immediately above a corresponding row of a layer bottom field. G.3.29 layer representation: A subset of VCL NAL units within an access unit that are associated with the same values of the dependency_id and quality_id syntax elements, which are provided as part of the VCL NAL unit header or by an associated prefix NAL unit, and the same value of the redundant_pic_cntsyntax element. One or more layer representations represent a dependency representation. Rec. ITU-T H.264 (01/2012) G.3.30 layer representation identifier: An integer value by which a particular layer representation inside a coded picture is uniquely identified. G.3.31 macroblock A 16x16 block of luma samples and two corresponding blocks of chroma samples of a picture or layer picture that has three sample arrays, or a 16x16 block of samples of a monochrome picture or layer picture. The division of a slice or a macroblock pair into macroblocks is a partitioning. G.3.32 macroblock-adaptive frame/field decoding: A decoding process for coded frames or layer representations in which some macroblocks may be decoded as frame macroblocks and others may be deco