http://def.wmo.int is used as a top level identifer for use in defining Unique Resource Identifiers (URIs). These identifiers are used to provide unique labels for namespaces, definitions, requirements and other items that need to be referenced unambiguously and do not need to resolve to URLs. All URIs formed using http://def.wmo.int will refer to this webpage.
The http://def.wmo.int/metce/2013 URI is the namespace for the Meteorological and Climatological Exchange (MetCE) model. The schema is located at https://schemas.wmo.int/metce/1.2/metce.xsd.
The http://def.wmo.int/collect/2014 URI is the namespace for the WMO Feature Collection model. The schema is located at http://schemas.wmo.int/collect/1.2/collect.xsd.
The http://def.wmo.int/opm/2013 URI is the namespace for the Observable Property model. The schema is located at http://schemas.wmo.int/opm/1.0/opm.xsd.
The http://def.wmo.int/wmdr URI is the namespace for the WIGOS metadata model. The schema is located at http://schemas.wmo.int/wmdr/1.0/wmdr.xsd