An unsigned 16-bit integer value. Version numbers less than 800 are for books that do not include a thumbnail image in the header.

Comments on the magic of 800

The value 800 may seem curious, but it may just indicate that thumbnails were added to the header format in the year 2003. Consider that: 800 == 0x320, LRF files are little-endian, and in a LRF hex-dump, 800 will appear as 2003.