scaling matrix. When this clause is invoked with a list of transform coefficient levels as the input, the sequence of transform coefficient levels is mapped to the transform coefficient level positions. Table 8-13 specifies the two mappings: inverse zig-zag scan and inverse field scan. The inverse zig-zag scan is used for transform coefficients in frame macroblocks and the inverse field scan is used for transform coefficients in field macroblocks. When this clause is invoked with a scaling list as the input, the sequence of scaling list entries is mapped to the positions in the corresponding scaling matrix. For this mapping, the inverse zig-zag scan is used. Figure 8-8 illustrates the scans. H.264(09)_F8-8 Figure 8-8 - 4x4 block scans. (a) Zig-zag scan. (b) Field scan (informative) Table 8-13 provides the mapping from the index idx of input list of 16 elements to indices i and j of the two-dimensional array C. Rec. ITU-T H.264 (01/2012) Table 8-13 - Specification of mapping of idx to Cij for zig-zag and field scan zig-zag field 8.5.7 Inverse scanning process for 8x8 transform coefficients and scaling lists Input to this process is a list of 64 values. Output of this process is a variable C containing a two-dimensional array of 8x8 values. In the case of transform coefficients, these 8x8 values represent levels assigned to locations in the transform block. In the case of applying the inverse scanning process to a scaling list, the output variable C contains a two-dimensional array representing an 8x8 scaling matrix. When this clause is invoked with a list of transform coefficient levels as the input, the sequence of transform coefficient levels is mapped to the transform coefficient level positions. Table 8-14 specifies the two mappings: inverse 8x8 zig-zag scan and inverse 8x8 field scan. The inverse 8x8 zig-zag scan is used for transform coefficient levels in frame macroblocks and the inverse 8x8 field scan is used for transform coefficient levels in field macroblocks. When this clause is invoked with a scaling 