[iaufwg] IAUFWG review of the new draft FITS Standard
Andreas Wicenec
awicenec at eso.org
Mon Mar 17 15:45:17 EDT 2008
Dear Bill and all Panel members,
thanks for all the effort put into the new document. This really is
an remarkable improvement of the
FITS standard document!
I do have a few suggestions, mostly regarding structure and wording:
- the last two sentences in section 3.1 should be dropped, since they
are not quite correct and don't add any
further information to the standard. If anything then one may
state that 'limitations due to hardware or software may restrict the
actual size of FITS files'.
- Section 4.1.1, last sentence: Why not turing this around and say
instead that Appendix A is the standard syntax description and the
text is the aid to explain it in natural
language?
- Section 3.3.1: change to "The last header block must contain the
END keyword *record* (defined in 4.4.1.1)"
... and that brings me to the more generic points:
- the usage of 'keyword' and 'keyword record' is kind of synonym in
the document and I think that this should not be the case. It is
clearly defined
in section 4.1.1 that a "keyword record shall consist of a
keyword name, a value indicator .....". This definition should be
used throughout the document
(including the Appendix A, see below). Thus I would at least
suggest to define 'Keyword' to be synonym to 'Keyword record' in
section 2.2, however
I would prefer that what is called 'keyword' now to be called
'keyword record'.
- I would suggest to change the structure of chapter 4 to follow the
logic of the document to go from higher level structures to more
details:
Thus I would suggest to change the the TOC to something like:
4 Headers
4.1 Keyword Records
4.1.1 Syntax
4.1.2 Keyword Name
4.1.3 Value
4.1.3.1 Character String Type
.......
4.1.4 Comment
4.2 Mandatory and Reserved Keyword Records
- Current section 4.1.2 could be dropped and the contents moved to
the introduction of the specific sections describing the components
of the keyword records.
- Current section 4.2 would then be section 4.1.3 and I would suggest
that it is explicitly stated that these are essentially type
definitions for FITS, including the formatting
rules. Thus I would suggest to add the word 'Type' to each of
the subsection headers.
- Obviously if we follow the structure of a keyword record, then
there should be a small section describing the comment field as well
(new section 4.1.4) and thus
splitting the Value/Comment section.
- Since units are not really well supported in FITS keyword
records ;-) I would suggest to move the current section 4.3 out and
put it into a separate main section. Since it
is in fact also describing units for the data sections (where it
is much more rigidly defined) this seems to be more logical and would
make section 4 more concise.
- Current section 4.4 is describing "Mandatory and Reserved Keyword
Records" and I think it should be called like this.
- Appendix A calls a keyword name a keyword_field, could it not be
keyword_name instead?
- Appendix A does not define the END keyword record...
As said already, I think the document is in pretty good shape
already, and what I've written are just suggestions. I would agree to
release the document also
without the changes, except the omission of the definition of the END
keyword record in appendix A.
Cheers,
Andreas
On 17.03.2008, at 18:19, William Pence wrote:
> Dear IAU FITS Working Group Members,
>
> It is now time for us (the IAU FWG) to conduct a final review of the
> proposed new FITS Standard document, leading eventually to a vote on
> whether or not to accept it as the official Standard. To jog your
> memories, here is a brief chronology of how we got to this point:
>
> 12/2006: Technical Panel is appointed (Chiappetti, Page, Pence,
> Shaw, and Stobie) to draft updates and clarifications
> to the FITS Standard.
> 07/2007: Technical Panel releases version 3.0 for comments
> 10/2007: Public comment period closes
> 11/2007: Technical Panel produces revised draft 3.0a
> 12/2007: Draft 3.0a sent to Regional FITS committees for review
> 02/2008: Regional committees generally endorse the new draft, with
> a few further comments
> 03/2008: Technical Panel produces revised draft 3.0b
>
> This latest draft of the FITS Standard is available for your review at
> http://fits.gsfc.nasa.gov/fits_draft.html along with other supporting
> documents, including,
>
> - A 12 page summary of the Technical Panel's response to the
> suggestions
> that were received during the public comment period and the Regional
> FITS committee reviews.
>
> - A 137 page color-coded document that highlights the differences
> between this latest draft version 3.0b and the current official
> version
> 2.1b.
>
> While reviewing this material, please keep in mind that all the
> proposed
> changes to the FITS standard are only recommendations at this point.
> Any IAU FWG member can propose further amendments to the document
> during
> this final review period, either to introduce new changes, or to
> revise
> or withdraw any of the currently proposed changes. If necessary, we
> will conduct procedural votes (which only require a simple majority to
> be accepted) on any proposed amendments prior to conducting a formal
> vote on the whether or not to accept the document as the new official
> FITS Standard.
>
> In particular, there are 2 issues that were raised back in November
> that
> we still need to resolve:
>
> 1. Arnold Rots suggested that it might be useful to add ISO-8601
> data-time to the recognized data types (presumably in Chapter 5 of the
> latest draft). In response, 3 of you (Shaw, Forveille, and Gabriel)
> felt that while this was perhaps worthy of further discussion, it is
> rather late in the process to make this change to the current
> draft, so
> it may be better to defer this to the next revision of the Standard
> (whenever that might be). Do the rest of you agree to defer this
> suggestion for now?
>
> 2. Mark Calabretta reiterated his desire for the new Standard to note
> any inconsistencies in syntax between previous versions of the
> Standard,
> either as an appendix or as footnotes throughout the document. An
> example might be where version 2 of the Standard turned the widely
> used
> convention of using a slash character to separate the keyword value
> and
> comment fields, into a requirement. The Technical Panel had
> declined to
> implement this suggestion, mainly on the grounds that it could
> require a
> significant effort to make a detailed comparison of all the different
> versions of the FITS Standard (and the original FITS papers too). So
> far, there has been no discussion of this issue here on this email
> list.
>
> My own feeling on this is that I would not object to adding
> footnotes to
> highlight a few cases where a current FITS requirement was not clearly
> stated in some previous versions of the Standard or in the original
> FITS
> papers. I don't think however that this issue warrants the time and
> energy that would be needed to try to document every change that has
> occurred in the history of FITS. Perhaps Mark (and others) could
> propose a list of instances where a footnote would be appropriate.
>
>
> So with this preamble, I would like to now open up the discussion
> period
> here on IAU FWG email list about any issues regarding the proposed new
> FITS Standard document. Please try to post your comments here within
> the next 2 to 3 weeks if possible, so as to not needlessly delay the
> final vote on this matter.
>
> regards,
> Bill Pence
> --
> ____________________________________________________________________
> Dr. William Pence William.Pence at nasa.gov
> NASA/GSFC Code 662 HEASARC +1-301-286-4599 (voice)
> Greenbelt MD 20771 +1-301-286-1684 (fax)
>
>
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