APEv2 specification
This is how information is laid out in an APEv2 tag:
| APE Tags Header | 32 bytes |
| APE Tag Item 1 | 10.. bytes |
| APE Tag Item 2 | 10.. bytes |
| ... | 10.. bytes |
| APE Tag Item n-1 | 10.. bytes |
| APE Tag Item n | 10.. bytes |
| APE Tags Footer | 32 bytes |
APE tag items should be sorted ascending by size. When streaming, parts of the APE tags can be dropped to reduce danger of drop outs between titles. This is not a must, but strongly recommended. Actually the items should be sorted by importance/byte, but this is not feasible. Only break this rule if you add less important small items and you don't want to rewrite the whole tag. An APE tag at the end of a file (strongly recommended) must have at least a footer, an APE tag in the beginning of a file (strongly unrecommended) must have at least a header. When located at the end of an MP3 file, an APE tag should be placed after the the last frame, just before the ID3v1 tag (if any).