VOUnits 1.0

[Norman Gray]

Sébastien and all, hello.

On 2011 Dec 16, at 23:31, Sebastien Derriere wrote:

>   It is a time of year when many are busy trying to find nice presents,
> so I am happy to share with you the version 1.0 of the VOUnits document,
> released as a working draft for discussion within the semantics WG,
> and destined to follow the IVOA recommendation process.
> http://www.ivoa.net/internal/IVOA/UnitsDesc/WD-VOUnits-1.0-20111216.pdf

Excellent -- a fine read.

>   A few points await your remarks and comments. I have set up a wiki page
> for this :
> http://www.ivoa.net/cgi-bin/twiki/bin/view/IVOA/DiscussionOnVOUnits
>   You can either post your comments on this page directly or reply to
> the semantics mailing list. The wiki page is not the RFC, but will be
> used as a justification of decisions made in the document, and linked
> from the RFC page when we get there.


The document mentions the unity library I wrote.  I can add a couple of extra comments about that.

The library was written with the following goals:

  * Producing formal grammars of the existing and proposed standard unit syntaxes, for reference purposes

  * Participating in this standardisation process by acting as a locus for experimentation with syntaxes and proposed standards

  * Discovering edge cases, producing machine-readable versions of the prescriptions in the standard, and producing test cases.

  * Producing parsing libraries which were fast and standalone, and so could be conveniently used by other software; this will act as an implementation of the eventual VOUnits standard

The grammars of the FITS, OGIP and CDS syntaxes are all in the form of yacc-style grammars.  These are associated with C, but the same syntax is used for other languages.  The unity library distributes a C and a Java library based on the same grammars; others should be reasonably easy to add.

I'll shortly add some comments to the wiki page.

The source is at <https://bitbucket.org/nxg/unity/>, and the snapshot downloads are there, too.

All the best,

Norman


-- 
Norman Gray  :  http://nxg.me.uk
SUPA School of Physics and Astronomy, University of Glasgow, UK