[UNITS] : (Was: Re: SED Data Model: Questions and Comments)

[Brian Thomas]

On Wednesday 16 February 2005 08:04 am, Pedro Osuna wrote:
> Dave and all,
> 
> maybe we should discuss this off-line, but as it has jumped off here,
> I'll keep on...
> 
> [...]FITS WCS paper one suggests that unit strings should be
> standardised[...]
> 
> yes, and again the problem is that some data providers do already have
> their units written in other formats. Some of them are inside very old
> "standard" names inside FITS files that will never be changed, just to
> give an example.

 Just my 2 cents... can't we satisfy everyone here by either:

 1. Simply analyzing  major unit string serializations, then finding the 
 underlying model, and using that within the IVOA DM? Each of the packages 
 could then have a "wrapper" that translates from the DM version to its
 particular serialization. 

 2.  Conversely, the DM group could "bless" major units serializations for 
 use. Blessed units serializations would have 1-to-1 translations to other 
 blessed serializations, and software, provided by the IVOA, would do the 
 work of translation. Within the DM, the type of "blessed" units serialization
 would be identified so the software would automatically be aware of what
 it was dealing with, e.g. a serialization of the DM (Q) in XML:

 <flux>
  <units type="UMDUnitsString">erg*m^-1*sec^-2</units>
  <value>10</value>
 </flux>

 =b.t.
 

-- 
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|                                     
| Dr. Brian Thomas                    
|                                     
| Dept of Astronomy                   
| University of Maryland-College Park 
|
| Phone: (301) 405-2312               
| Fax: (301) 314-9067                 
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