verse 8x8 Cb or Cr block scanning process for ChromaArrayType equal to 3 This process is only invoked when ChromaArrayType is equal to 3. The inverse 8x8 chroma block scanning process is identical to inverse 8x8 luma block scanning process as specified in clause 6.4.5 when substituting the term "luma" with the term "Cb" or the term "Cr", and substituting the term "luma8x8BlkIdx" with the term "cb8x8BlkIdx" or the term "cr8x8BlkIdx" in all places in clause 6.4.5. 6.4.7 Inverse 4x4 chroma block scanning process Input to this process is the index of a 4x4 chroma block chroma4x4BlkIdx Output of this process is the location (x,y) of the upper-left chroma sample for a 4x4 chroma block with index chroma4x4BlkIdx relative to the upper-left chroma sample of the macroblock. The inverse 4x4 chroma block scanning process is specified by X = InverseRasterScan( chroma4x4BlkIdx, 4, 4, 8, 0 ) (6-21) y = InverseRasterScan( chroma4x4BlkIdx, 4,4,8,1 ) (6-22) 6.4.8 Derivation process of the availability for macroblock addresses Input to this process is a macroblock address mbAddr. Output of this process is the availability of the macroblock mbAddr. NOTE - The meaning of availability is determined when this process is invoked. The macroblock is marked as available, unless any of the following conditions are true, in which case the macroblock is marked as not available: mbAddr < 0, mbAddr > CurrMbAddr, the macroblock with address mbAddr belongs to a different slice than the macroblock with address CurrMbAddr. 6.4.9 Derivation process for neighbouring macroblock addresses and their availability This process can only be invoked when MbaffFrameFlag is equal to 0. The outputs of this process are: mbAddrA: the address and availability status of the macroblock to the left of the current macroblock, mbAddrB: the address and availability status of the macroblock above the current macroblock, mbAddrC: the address and availability status of the macroblock above-right of the current macroblock, mbAddrD: the address and availability status of the