VOUnits 1.0 revised version

[Mark Taylor]

On Tue, 22 May 2012, Sebastien Derriere wrote:

>   Hello all,
> 
>   Here is a revised version of the VOUnits 1.0 document, following comments
> received on the previous version and gathered on the wiki, as well as
> discussions in the interop session in Urbana :
> http://www.ivoa.net/cgi-bin/twiki/bin/view/IVOA/DiscussionOnVOUnits
>   The document will be also uploaded in the ivoa doc repository.
> 
>   Changes are listed in the Annex A. The main change is to accomodate
> possible numerical prefixes to have VOUnits like "2.54 cm".
>   Most of the proposal is still very close to the FITS 2010 paper.
> The proposed roadmap is to have two weeks for discussion on the semantics
> mailing list or on the wiki page, before moving to PR and opening the
> official RFC.

Hi Sebastien et al.,

Here are a few comments on the VOUnits document (May 22 Draft).
Mostly these are pretty minor, on the whole it looks good.

Sec 1.2:
  I'm not quite sure what the distinction, if any, is supposed to be
  between "symbol"/"sym" and "label".

Sec 1.3:
  "and be as compliant..." -> "and will be as compliant..."

Sec 2.5:
   IAU 2000 is referenced in the text, but not in the References
   (though IAU 1989 is in the References).

Section 3:
   References to "Tab. n" in the tables confused me to start with -
   I think it means the tables in the relevant external documents.
   It's valuable to have these tables in their existing compact
   form, but a bit of explanation about the format before the first
   one might improve clarity.

Table 2:
   I don't quite understand the bottom part of the first (largest)
   row of this table, i.e. the part below "rad, sr".
   Is it additional notes/deviations from what's in the rest of that
   row?  Why is the VOUnits part blank?  Some annotation in the
   first column there could clarify.

Table 3:
   Formatting - the line "da, h, k, ..., E" should be directly
   below "d, c, m, ... a"?  Currently there's a gap between them.

   Final column, penultimate row: "P" has wrong font in
   "all (except P for a)".

Table 4:
   One usage of "uarcsec" has wrong font.

   Should "jansky" have a capital J?

Section 3.5:
   Usage of an empty string for "no unit".  Is this supposed to be
   as distinct from the absence of a unit string (e.g. unit="" as
   opposed to no unit attribute in VOTable FIELD)?  If so I doubt
   that it will work well, since different scenarios may or may not
   provide the option of a null-like value for units.
   If the intention is just to make it clear that you don't write
   explicitly "unitless" or something like that, it sounds fine,
   but it would be worth noting exactly what's meant here.

Table 3.6:
   s/asterix/asterisk/g

   "MUST never two" - some missing text?

Section 3.7:
   "simple or double quotes" - should that be "single or double quotes"?

Acknowledgements:
   "proving comments" -> "providing comments"?

Mark

--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/