seaman at noao.edu
Mon Oct 24 15:51:35 PDT 2005
Could somebody comment on the relationship between http://
www.ivoa.net/internal/IVOA/IvoaUCD/UCD-1.9.9b.pdf and http://
www.ivoa.net/Documents/latest/UCD.html? Is the former obsolete? It
hasn't been updated in two years.
In any event, I don't see any discussion of a versioning strategy.
Unfortunately, I also can't seem to get a search to work on the list
archive (http://www.ivoa.net/forum/ucd). Surely this topic has been
discussed (likely in gory detail)? Or is there some notion of "once
UCD, always UCD"?
The recent discussion about UCD maintenance seems to me to be
orthogonal to the question of explicit versioning. Are new UCDs
simply added to the end of a list that preserves no historical
memory? Or are new UCDs appended to only the latest version of the
list? Are UCDs ever removed from the list? Are their names or
locations in the hierarchy never to be changed?
And is the interpretation of a document that uses UCDs going to vary
as the master list changes over time? The process for adopting UCDs
is intended to be very conservative, but even so, one imagines that
some UCDs will be adopted that will later be rethought. Note that
even if the UCDs associated with a particular document (or image or
catalog) don't change, that the nuances of the interpretation of
these items might change as new - unselected - UCD options are added
to the master list. An assertion versus three options may turn into
an assertion versus six options.
I gather there is some thought of occupying UCD-space only until we
enter the promised land of the ontology-sphere. One might be
forgiven, perhaps, for imagining that this may well take a sizable
fraction of the Biblical 40 years of wandering, however. That being
the case, what provisions are in place to allow UCDs to thrive in the
Could someone summarize how UCD versioning is - or is not - supposed
to work? Alternately, feel free to point me toward pertinent
More information about the ucd