This is the static register (index) of GA's ontologies. Its purpose is to present the static URIs to each of them which is particularly useful for machines that wish to automatically index them, more so than than humans who can search for them manually.
This register is visible, here, in HTML for humans and also in RDF for machines:
These ontologies are Geoscience Australia's ontologies for internal and external use. They are all formulated according to the Web Ontology Language (OWL) which is itself represented in RDF. The ontologies are able to be searched using the SPARQL query language if cached in an RDF triplestore. Shortly (mid 2017) GA will provide a triplestore containing the content of all of these ontologies.