ℹ️ The possibility of addressing this issue in the scope of the Core Location Vocabulary is discussed in SEMICeu/Core-Location-Vocabulary#2 , from which the following issue description is taken.

For this purpose, GeoDCAT-AP v1.0 uses property dct:conformsTo.

Since dct:conformsTo is a very general property, the fact that the object is a spatial / temporal reference system is currently addressed by using dct:type with the relevant code list values from the INSPIRE Glossary, as shown in the following example:

a:Dataset a dcat:Dataset ;
  dct:conformsTo a:SpatialReferenceSystem .
  
a:SpatialReferenceSystem a dct:Standard ;
  dct:type <https://inspire.ec.europa.eu/glossary/SpatialReferenceSystem> .

Moreover, an experimental RDF representation of reference system from the OGC CRS Register has been developed, mapping additional information (as the "name" of the CRS).

It might be desirable to have a more specific property than dct:conformsTo and/or use a stronger typing rather than using dct:type with a term from the INSPIRE Glossary.

In such a case, an initial proposal for the definition of specific classes / properties is documented here:

https://joinup.ec.europa.eu/mailman/archives/dcat_application_profile-geo/2015-July/000157.html

⚠️ The Git repository including the the mapping proposal referred to from the mail above has been moved to GitHub: https://github.com/SEMICeu/epsg-to-rdf

Moreover, the new version of the W3C Time Ontology includes a class time:TRS that could be used to type temporal reference systems.