  Enhancing interoperable data access to radio data has become a science
priority within the International Virtual Observatory Alliance (IVOA). This
lead to the foundation of the IVOA Radio astronomy Interest Group. Several
radio astronomers and project scientists enrolled in various projects (NRAO,
ASKAP, LOFAR, JIVE, ALMA, SKA, INAF, NenuFAR, etc.) have joined. Together they
are paving the way to a better integration of their services in the virtual
observatory (VO) infrastructure and propose extension of IVOA standards to help
achieving this goal. Calibrated radio datasets such as cubes, images, spectra
and time series can already be searched and retrieved using the ObsCore/ObsTAP
specification defined in the IVOA, or by data product-specific services like
SIAv2, SODA, SSA and ConeSearch. However, properties of radio visibility data
are not fully implemented in the VO landscape yet. We need specific features to
refine data discovery and selection that are adapted to radio astronomers'
need. In this context the VO team at the Centre de Donn\'{e}es astronomiques de
Strasbourg (CDS) proposes to consider the ObsCore/ObsTAP specification and to
establish cross-walks between the ObsCore and the existing Measurement Set (MS)
metadata profile for data discovery of radio visibility data (VD). In order to
account for the difference in granularity between radio VD datasets and
science-ready datasets of the VO, the approach splits a MS data file into a
list of datasets served by an ObsTAP service, thus enabling coarse grain
discovery in the multi-wavelength context. Radio specific metadata such as
number of antennae, frequency ranges, $uv$ plane coverage plots,
frequency-phase and frequency-amplitude plots, primary and synthesized beams
are also provided either by adding column metadata or by using the DataLink
technique.
