ExFAT overview: http://www.ntfs.com/exfat-overview.htm
Reverse engineering on exFAT: http://events.linuxfoundation.org/images/stories/pdf/lceu11_munegowda_s.pdf
Design of the FAT filesystem: https://en.wikipedia.org/wiki/Design_of_the_FAT_file_system
Microsoft FAT32 format specification: http://msdn.microsoft.com/en-us/windows/hardware/gg463080
About lengths: https://rshullic.wordpress.com/2014/06/01/exfat-vdl-feature-two-data-lengths-file-pre-allocation-support/