BOF version 3 {4} endianness 00 = big, 01 = little {6} (tag directory|tag) {2-256} (2 byte tag length value + tag name which can be of zero length. Theroetically tag name could be ~65k long but limiting to 256 bytes for signature efficiency as highly unlikely to be greater. Scope to extend if necessary though). String "%%%%"
EOF: 8 null bytes