[fitsbits] Start of the ''Hierarchical Grouping' Public Comment Period

[Mark Calabretta]

On Mon 2007/04/09 15:17:45 -0400, William Pence wrote
in a message to: fitsbits at donar.cv.nrao.edu

>This is to announce the start of the 30-day Public Comment Period on the
>'Hierarchical Grouping' FITS convention that has been submitted for

Notes on "A Hierarchical Grouping Convention for FITS".

The documentation is well written and leaves little doubt as to how the
convention would be implemented in software.  The API described in
Sect. 7 is also very useful in this respect.  I have only a few minor
comments.

* Some comment needs to be made on fragility of references to external
  FITS files, especially those using http:// or ftp:// URLs.  What is
  supposed to happen if one of these references can't be satisfied?

* There should be some mention of the need to avoid recursive grouping;
  i.e. a group cannot be a member of itself either directly or
  indirectly.

* Can a HDU be added more than once to a grouping table?

* In Sect. 2.2 it should be noted that EXTVER does not have to be
  sequential.  The caption for example 2 incorrectly concludes that
  "it is the seventh group table" on the basis that EXTVER = 7.

* Sect. 3, there needs to be some discussion on the meaning and use of
  the index "n" in GRPIDn and GRPLCn.

* If grouping table A is a member of grouping table B, and grouping
  table B is a member of grouping table C, then should there be a
  GRPIDn/GRPLCn in grouping table A to say that (indirectly) it is also
  a member of grouping table C?

* I suggest extending example 2 by illustrating a small portion of the
  grouping table itself, i.e. in rows and columns with column headers as
  fv would.

* Appendix 1 seems to define keyword values with no associated
  keyword(s).

* Sect 7 (third para) has "a given HDU may be referenced by up to 999
  grouping tables simultaneously".  Where does this limit come from?


Typos noticed in passing:

p3:  "values, Thus, this" ->
     "values.  Thus, this"
p4:  "mne-monic" -> "mnemonic".
p9:  Writing 'MEMBER LOCATION' for the value of MEMBER_LOCATION (etc.)
     makes them look like keyvalues, which they are for TTYPEn, but not
     in this situation.  I suggest writing MEMBER_LOCATION (etc.) in
     italics instead.
p11: "CFITSIO software library that is maintained by" ->
     "CFITSIO software library which is maintained by"
p11 & 13: Use ``xxx'' for double-quoting in latex.
p11: Missing full-stop after "Hierarchical Grouping Convention for FITS".