JPEG Huffman encoder AC0
| HCODE66 | Huffman code 66 8 least significant bits of the Huffman code. If the Huffman code is less than 8 bits long, the unused bits must be 0. |
| HLEN66 | Huffman length 66 Number of bits in the Huffman code HCODE66 minus 1. |
| HCODE67 | Huffman code 67 8 least significant bits of the Huffman code. If the Huffman code is less than 8 bits long, the unused bits must be 0. |
| HLEN67 | Huffman length 67 Number of bits in the Huffman code HCODE67 minus 1. |