VOResource 1.1 says in the documentation of the subject element: "Terms
for Subject should be drawn from the Unified Astronomy Thesaurus
(http://astrothesaurus.org)."
This prescription is not suffient in practice; for many reasons, we
cannot really use the UAT concept URIs (for instance,
http://astrothesaurus.org/uat/11 for "The relative amount of a given
chemical element with respect to other elements") in VOResource. The
label (in the example, "Abundance ratios") is not necessarily stable and
suffers from case and potentially punctuation issues.
To have a solid foundation for UAT use in VOResource, a specific scheme
has recently been endorsed in the VO, "Adopting the UAT as an IVOA
vocabulary", https://ivoa.net/documents/uat-as-upstream/. This is what
should now be used in VOResource, and hence the document should contain
a pointer to the UAT adoption note. This erratum introduces these
pointers and updates an example to the modern practice.
Impact Assessment:
At the moment subject simply is not machine-readable and hence its
content is treated as plain text. TOPCAT, for instance, translates
subject constraints into
LOWER(res_subject) like '%keyword%'.
These will obviously keep working as before (except if a data provider
actually had introduced upstream UAT URIs; none has, so far).
The syntax chosen in the UAT note – words separated by hyphens – also
makes queries using ivo_haswords work as before. During the review
phase of this erratum, the TAP service at http://dc.g-vo.org/tap carries
table rr.uat_concept that reflects how rr.res_subject will look like
once the UAT migration is finished. To illustrate the effects on
queries using haswords, try:
select distinct uat_concept from rr.subject_uat
where 1=ivo_hasword(uat_concept, 'radio')
there.
Hence, we do not expect noticable negative impact. On the other hand, a
migration to the scheme forseen here will enable many useful
applications, starting from reliable keyword matching to semantics-based
query expansion to subject mapping for interdisciplinary metadata
repositories (cf.
https://blog.g-vo.org/semantics-cross-discipline-discovery-and-down-to-earth-code.html).
Rationale:
VOResource 1.1 says in the documentation of the subject element: "Terms for Subject should be drawn from the Unified Astronomy Thesaurus (http://astrothesaurus.org)."
This prescription is not suffient in practice; for many reasons, we cannot really use the UAT concept URIs (for instance, http://astrothesaurus.org/uat/11 for "The relative amount of a given chemical element with respect to other elements") in VOResource. The label (in the example, "Abundance ratios") is not necessarily stable and suffers from case and potentially punctuation issues.
To have a solid foundation for UAT use in VOResource, a specific scheme has recently been endorsed in the VO, "Adopting the UAT as an IVOA vocabulary", https://ivoa.net/documents/uat-as-upstream/. This is what should now be used in VOResource, and hence the document should contain a pointer to the UAT adoption note. This erratum introduces these pointers and updates an example to the modern practice.
Impact Assessment:
At the moment subject simply is not machine-readable and hence its content is treated as plain text. TOPCAT, for instance, translates subject constraints into
These will obviously keep working as before (except if a data provider actually had introduced upstream UAT URIs; none has, so far).
The syntax chosen in the UAT note – words separated by hyphens – also makes queries using ivo_haswords work as before. During the review phase of this erratum, the TAP service at http://dc.g-vo.org/tap carries table rr.uat_concept that reflects how rr.res_subject will look like once the UAT migration is finished. To illustrate the effects on queries using haswords, try:
there.
Hence, we do not expect noticable negative impact. On the other hand, a migration to the scheme forseen here will enable many useful applications, starting from reliable keyword matching to semantics-based query expansion to subject mapping for interdisciplinary metadata repositories (cf. https://blog.g-vo.org/semantics-cross-discipline-discovery-and-down-to-earth-code.html).