[fitsbits] The CONTINUE and HIERARCH Conventions Public Comment Periods

[William Pence]

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 are:

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
-- 
____________________________________________________________________
Dr. William Pence                       pence at milkyway.gsfc.nasa.gov
NASA/GSFC Code 662       HEASARC        +1-301-286-4599 (voice)
Greenbelt MD 20771                      +1-301-286-1684 (fax)