LC's NoSpam Newsreading account wrote:
I have inspected the PDF description of the HIERARCH Convention in the
registry and I have the following questions/comments.
....

3) Although defined in a self-consisent manner, the content of
section 2 is DEFINING AN ALTOGETHER DIFFERENT CONVENTION !

Both of these (the ESO hierarchical usage, and the long keyword name
usage) are special cases of the more general convention that has been
implemented in CFITSIO since 1999. The general convention looks like this:

HIERARCH Effective Keyword Name = value / Comment String

where Effective Keyword Name represents any string of ASCII text
characters (except the equal sign character which is not allowed because
it serves as the delimiter between the Effective Keyword Name and the
value. Examples of this general convention a

HIERARCH Last Name = 'Pence'
HIERARCH $PATH = '/usr/local/bin /usr/bin/'
HIERARCH Minimum Disk Space Requirement = 3000000 / bytes

In this general case there are no restrictions on what characters are
allowed in the Effective Keyword Name, except for the equal sign
character, and that it must fit within the 80-character keyword record.
In the CFITSIO API, programs can read and write keywords such as "Last
Name" or "$PATH" in exactly the same way as they would read or write a
standard keyword like "OBJECT" or "DATE". The application program
itself does not need to know how the HIERARCH convention works.

In the ESO special case, the Effective Keyword Name consists of a series
of tokens that each conform to the requirements of a FITS keyword name.
The first token defines the name space, and the remaining tokens form
a hierarchical classification of the keyword.

In the long keyword name special case, embedded spaces are not allowed
to avoid confusion with the ESO usage, and to avoid problems that can
arise in handling the embedded spaces in certain circumstances (e.g., it
can make it more difficult to parse the keyword record).

Bill
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__________________________________________________ __________________
Dr. William Pence
NASA/GSFC Code 662 HEASARC +1-301-286-4599 (voice)
Greenbelt MD 20771 +1-301-286-1684 (fax)