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OGC Seeks Comments on "NIL Extension" to Geography Markup Language (GML)


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Release Date: 
Wednesday, 24 October 2012 UTC

24 October 2012. The Open Geospatial Consortium (OGC®) seeks public comment on the candidate "GML-NIL profile" of the OGC Geography Markup Language (GML) Encoding standard. GML is a widely used XML grammar for encoding information about geographical features. The GML-NIL profile provides a way to allow data providers to make a best effort to supply data according to an application schema, even if they do not have values for all feature properties. This is achieved by marking the application schema as a whole as ‘nillable=true’ and using OGC ‘nil’ URIs in links for missing data. This reverses the usual pattern which has a default value of nillable=false.   

The GML-NIL pattern of use has been used informally for several years in Earth and environmental science applications, and this candidate standard merely aims to formalize and document the practice. It is expected to be useful in many applications where a heterogeneous community wishes to enable participation by a wide variety of members with different capabilities and data sources. The submission team is composed of members of the GeoSciML project.

The candidate OGC GML-NIL standard document is available for review and comment at

The closing date for comments will be 23 November 2012.

The OGC is an international consortium of more than 465 companies, government agencies, research organizations, and universities participating in a consensus process to develop publicly available geospatial standards. OGC Standards support interoperable solutions that "geo-enable" the Web, wireless and location-based services, and mainstream IT. OGC Standards empower technology developers to make geospatial information and services accessible and useful with any application that needs to be geospatially enabled. Visit the OGC website at