ZiPatch File Structure
From FFXIV Classic Wiki
ZiPatch File Header 91 5A 49 50 41 54 43 48 0D 0A 1A 0A
uint dataSize (Little Endian) byte data[dataSize] byte crc[4]
crc is standard CRC32 checksum (RFC 1952) of the data block
string type (data[0..3]) "FHDR" (File Header) "APLY" "APFS" "ETRY" (Entry File) "ADIR" (Add Directory) "DELD" (Delete Directory)