Simple Cone Search version 1.03 Proposed Erratum 2: Drop mandatory version for VOTable response

Authors: Marco Molinaro, Markus Demleitner

Date last changed: 2021-11-19

Date accepted: 2022-01-26

Rationale

The Simple Cone Search specification, version 1.03, at Section 2, bullet 2, requires that compliant services return VOTable version 1.0 or 1.1.

This forces server-side software to still support a standard outdated since the release of VOTable 1.2 in 2009, and it prevents the use of several modern VOTable features relevant to SCS content, for instance TIMESYS and GROUP children of RESOURCES-s as required by Datalink.

This Erratum proposes to legalise the already reasonably widespread practice of returning more modern VOTables from SCS services.

Erratum Content

In Section 2, bullet 2 of Simple Cone Search - Version 1.03 replace the sentence:

The XML content of the response must be compliant with VOTable schema, version 1.0 [VOTable v1.0] or 1.1 [VOTable v1.1].

with

Simple Cone Search services MUST return VOTable version 1 documents.

Impact Assessment

We believe no software is in current use that will fail when encountering elements from VOTable 1.2 and later. Hence, lifting the limitation to 1.1 should have no operational impact (in the sense of causing client fail that were working correctly before). In addition, most VOTable clients traditionally already employed lenient parsing as forseen by the schema versioning policies.

On the other hand, the Erratum will enable, for instance, proper declaration of time metadata, attaching additional data resources to table rows through datalink, or data model annotation in tables returned through SCS, which for advanced clients substantially increases the usefulness of this protocol.