Robert Hanisch wrote:
..I believe II share some responsibility for the invention of HIERARCH (I
think I first suggested it at a FITS WCS meeting in Charlottesville, ca.
1989)..

I didn't remember who suggested the keyword HEIRARCH. I am not surprised
to learn that it was you, Bob, and I am not surprised that the name
HEIRARCH originated at that meeting. My memory is that the main purpose
of that meeting (January 1989?) in Charlottesville was to discuss what
we now call World Coordinate Systems, but we discussed many other ideas
for FITS.

However, there is more to say about the origin of the HEIRARCH idea. The
basic idea of a heirarchical namespace for FITS is ten years older; it
dates from the time of the first FITS files in 1979, when Eric Greisen
prototyped the idea in NRAO production software for VLA mapping. Two
years later Greisen's implementation was illustrated in the original
Wells-Greisen-Harten FITS paper in A&A June-1981, in Figure-1 on p.370:

INSTRUME= ‘VLA ' / NRAO(CV) VLA MAPPING.PROGRAMS
DATE-MAP= ‘16/10/78’ / MAP CREATION DATE DD/MM/YY
DATE = ‘27/05/79’ / MAP WRITiNG DATE DD/Vf/YY
ORIGIN = 'NRAO(CV) PGM=DEC2FITS(V1)’
HISTORY VLACV MAP METHOD=’FFT’ DATA=’OBS. VISIBILITY’
HISTORY VLACV MAP WCONU= O.00000E+OO WCONV= O.000000E+O0 TCONU= 0

Greisen used HISTORY in his implementations of the idea, as shown in the
last two header lines above. His implementation allowed the possibility
of more than one keyword=value on a heirarchical keyword line. What we
have in the example above are internal variables and options for an
imaging software package called VLACV. (This was before the AIPS
project; the code was batch software running on an IBM mainframe; note
the DATE keyword values.) The keywords are for the 'MAP' sub-namespace
of the 'VLACV' package. Anyone who has ever looked at a header written
by NRAO's AIPS package in the past 25 years knows that Greisen later
used the same scheme for AIPS.

I have always regretted that Eric Greisen, Ron Harten and I did not
include text in the original FITS paper that would have discussed those
two header lines in Figure-1. I think that we should have advocated use
of the heirarchical namespace idea by other astronomy groups.

-Don