JPEG Huffman encoder AC0
| HCODE42 | Huffman code 42 8 least significant bits of the Huffman code. If the Huffman code is less than 8 bits long, the unused bits must be 0. |
| HLEN42 | Huffman length 42 Number of bits in the Huffman code HCODE42 minus 1. |
| HCODE43 | Huffman code 43 8 least significant bits of the Huffman code. If the Huffman code is less than 8 bits long, the unused bits must be 0. |
| HLEN43 | Huffman length 43 Number of bits in the Huffman code HCODE43 minus 1. |