New guide: XML catalogs for working with ISO/TC 211 schemas

ISO/TC 211 schemas are served from a single, reliable, and permanent source — this site — so xsi:schemaLocation attributes and xsd:import elements always resolve to the normative schema documents. But when you work offline, when a repository is temporarily unreachable, or when repeated downloads slow your processing down, an XML catalog is the right tool for the job.

A new guide is now available in the Docs section: XML Catalogs.

The guide was authored by Heidi Vanparys of KDS (DK), supported by Tobias Spears (CA), Magnus Karge (NO), and Peter Parslow (GB).

What the guide covers

Mapping namespace URIs. Using the catalog uri element to point an XML namespace — for example https://schemas.isotc211.org/19115/-1/mdb/1.3 — at a local copy of the schema document that declares it.

Mapping schema locations. Using the system element to redirect schemaLocation URLs to local files, including a discussion of when uri versus system entries are appropriate and how to support both for maximum tool compatibility.

A starter catalog for the geospatial domain. Ready-to-adapt entries for the core schemas that ISO/TC 211 schemas commonly reference: XML Schema, xml.xsd, XLink, GML 3.2, and the ISO 19139 gco/gmd/gmx/gsr/gss/gts schemas.

Why it matters

XML validators, IDEs, and other tools fetch schema definitions automatically from the URLs declared in instance documents. Local catalog mappings keep that workflow working when connectivity does not cooperate, eliminate redundant downloads, and avoid the errors and warnings that occur when the same schema is loaded more than once from different locations.

The guide joins the Docs section, which collects practical guidance for implementers of ISO/TC 211 schemas.

This action is performed by Ribose.