An STC "when" and "where" example

[Rob Seaman]

Alasdair Allan writes:

> Time isn't necessary under all circumstances.
> Wavelength isn't necessary under many circumstances.
> [observer's location] Not necessary in many circumstances.
> Errors are always helpful, but not necessary in all cases.

And one imagines spatial coordinates aren't necessary under all 
circumstances :-)

Again, STC appears to allow making each of these optional.  More to the
point, this is an opportunity for VOEvent to inform the STC 
specification.

>> Giving minimal, sketchy information may be fine for some of your
>> clients because they know exactly what you mean or they don't require
>> great accuracy, but there may be other potential clients who cannot do
>> anything with it because there isn't enough information; the planetary
>> community is an obvious example.
>
> Then they should ignore the document as it doesn't have enough 
> meta-data
> for their purposes, those clients that can make use of the document 
> can do so...

I believe Arnold is using "client" in its colloquial sense and Alasdair 
in its
computer science sense.  Arnold is echoing my point that either VOEvent
supports a rich coordinate facility or it will not be useful for 
conveying all
types of events that are useful to specific astronomical 
sub-communities.

On the other hand, Alasdair is suggesting (I believe) that multiple 
software
clients, perhaps written in multiple languages, might require differing 
levels
of support for the VOEvent standard itself for various purposes.

It should be an interesting workshop...

Rob Seaman
NOAO