Shape: description enhancements

[mcdittmar]

I'm looking over different uses of the Shape concept ( CAOM, STC, etc ). In reading this description, I'm noticing a couple enhancements which could be made to the descriptions.

ShapeSerialization enumeration

• MOC:
  • should include a reference to the MOC standard
  • The description states "serialized as a S-MOC". The MOC standard consistently uses "SMOC" when referring to the Spatial MOC. Perhaps the label and description should use "SMOC" as well.
  • SMOC 'should' be in equatorial ICRS, but it is not clear how that info is conveyed in the ASCII format. The Shape here, would allow that to be indicated though, so probably not an issue, just maybe something to clarify for users (see SpaceSys comment)
• STCS:
  • a better reference might be the STC-S DAL standard (https://www.ivoa.net/documents/STC-S/20130917/index.html) Section 5.2.
    • I see this is a WD document.. and recall this has come up in recent TCG meetings, but don't recall if any decision was made about what to do with it.
  • contrary to the SMOC, "STC-S" is the common name for this format.. perhaps the '-' is not allowed in Enumeration labels?
  • This format includes the Frame info (e.g. ICRS BARYCENTER ), see SpaceSys comment
• POLYGON:
  • Is this for a DALI Polygon? I think it needs to be explicit about the format expectations, or it will be hard for clients to decode it. Gerard mentioned in the recent Running meeting that there are other standard Polygon serializations in the wild.

Shape.spaceSys

• MOC and STC-S have Space System information baked into the serialization or definition. How does this interact with this required field?
  • ie: if I'm a provider serving an STC-S shapes ("Circle ICRS GEOCENTER 179.0 -11.5 0.5"), do I also have to provide a corresponding SpaceSys instance?