Notes on DM1 session, Tuesday 26 May, 14:00-15:30 / M.Louys,H.Wozniak
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HW: H. Wozniack		FC: F. Chéreau
AM: Alberto Micol		FB: F. Bonnarel
GL: Gerard Lemson		IC: I. Chilingarian

S. Derriere + F. Oschenbein Units
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Quantity = UCD AND value AND unit AND datatype

Basic symbols are case sensitive!
disentangle rewriting of units expression from quantity conversion.
quantity transformation : frequency to wavelength (need a formula and 
dimensional analysis to check the transform)

IAU recommandations, Heasarc, Vizier, FITS

Existing librairies (AST, Vizier) already allow for units string transcription and quantity conversions. 

Three levels :
	- map existing user/archival data to VO standards
	- exchange within VO protocols
	- display in end user applications

writing rules : astronomical publications vs ascii
discussion :
Igor :
. units conversion and quantity conversion are sometimes mixed (Jy)
depends on wavelength

Arnold : make use of FITS standard Sect. 4.3 to determine the list of units supported by the VO

Debate on quantity conversion vs units conversion. In 
frequency-wavelength related quantities, conversion often need to know the wavelength. 
For magnitudes, system (Vega, AB) and filter must be known.

HW :Problems with dimensionless units : log units (that are log of ratio of similar quantities), (ster)radians, etc. How to code them?

AM : The VO should restrict or at least support only a restriction subset within the protocol.
what do you put on the wire?
Should not support all the complexity in the transport layer( DAL protocols) .

M. Louys: Utypes
--------
";"character for concatenation in  models combinations : 
A.M: Should not we alias this structure as the location name ( in the example).
FC: why using STC strings namely, as we are importing the STC schema. 

ML: discuss this topic explicitely on the list.

GL : name space verificalion for a set of reserved words: semantics WG already discussed some of the issues
action : ML to discuss with Vocabulary people (Norman G.)
(...) a lot of discussions there...

François B : need to have and use rules. known how to go from the uml to utype (input from the Theory IG).

A. Rots
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Update of STC S
A converter from STC-X to STC-S and reverse. 
STC library developped in JAva. 
new classes available for summer

G. Lemson
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Summary of DM aspects/questions in SimDB project.
Agreed : The Simulation DM to be examined and pushed as a standard by the DM group.