Dr. Dobb's Journal, May 1996, “Improving USENET News Performance” describes the original design of the Virtual Filesystem for USENET News.

Header files
The following header files contain useful things for filesystem handlers:
  • <devctl.h> — contains the definition for devctl(), and also defines the component flags used to create a command.
  • <dirent.h> — contains the directory structure type used by readdir().
  • <sys/dcmd_blk.h> — contains the DCMD_FSYS_* devctl() block commands (see the Devctl and Ioctl Commands reference).
  • <sys/disk.h> — defines partition_entry_t.
  • <sys/dispatch.h>, <sys/iofunc.h> — Used by resource managers.
  • <sys/fs_stats.h> — defines the fs_stats structure returned by the FSYS block command DCMD_FSYS_STATISTICS.
  • <sys/mount.h> — defines the mount flags.
  • <tar.h> — defines the layout of the .tar header.
  • <zlib.h> — contains the definitions for the transparent compression library.
See the following functions:
  • gzclose()
  • gzopen()
  • gzread()
  • gzseek()

as well as the following in the QNX Neutrino C Library Reference:

An excellent introduction to cryptography is Applied Cryptography — Protocols, Algorithms, and Source Code in C by Bruce Schneier (John Wiley & Sons, Inc., 1996, ISBN 0-471-11709-9)