New SIA v2 proposal

[Patrick Dowler]

On 14/09/15 11:20 PM, Walter Landry wrote:
> I am not comfortable with this approach.  If you make people put
> something in that slot that is not 'NULL', it does not feel like a
> NULL.  VOTable defines +Inf and -Inf, and it would have the expected
> effect.  Users do not understand NaN as well as infinity.

<editor-hat>

It is really unfortunate that someone who knew that +Inf and -Inf were 
supported (I didn't) wasn't there in Sesto. Still, as editor I should 
have looked more closely at the VOTable spec before writing those 
examples :-(

Anyway, the principle being (incompletely) adopted is that parameter 
values should be serialised the same way as VOTable arrays (of numbers 
in this case). The phrase "range values are encoded using the VOTable 
array serialisation" means that NaN, +Inf and -Inf are all allowed (we 
didn't explicitly say they are not), although we don't give any such 
examples except for unspecified bounds aka NaN.

** So: Walter is completely right and the examples should be fixed to 
show use of +inf and -Inf. **

As for your specific comfort with NaN usage here, the real problem is 
that we were wanting to allow "unspecified bound" which turns out to be 
NaN. I agree it has some ugly all over it...  Allowing unspecified 
bounds (NaN) really adds no value at all at this point since you have to 
put something in the param value anyway; that could go.

</editor-hat>

<tcg-hat>

The changes in the PR in response to the TCG review will be reviewed 
during a TCG review phase. Since this is an issue of compatibility 
between RECs from different WGs it seems appropriate to be aired in that 
context.

</tcg-hat>


-- 
Patrick Dowler
Canadian Astronomy Data Centre
National Research Council Canada
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