The CFHT FITS header registry is a single C header file,
fh_registry.h. The registry is an optional CFHT-specific extension to the our
FITS handling library libfh
(which is general, and has a similar interface to the ``cfitsio'' package.)
It is our goal to list all keywords in use by the CFHT data acquisition system
in the registry. Since ``handlers'' in the data acquisition system are compiled
against the current version of fh_registry.h, it should be authoritative and correct
or our source tree will not build.