It has a unique header, but the index entries table is similar to the
other formats. It does *not* set the high bit to indicate NC; instead,
it uses the same method as CISOv2, where the compressed block size
matches the uncompressed block size.
Compression algorithm is lzo1x.
TODO:
- JISO supports NC areas. Figure this part out.
- Add LZO to extlib.
