[postgis-users] GML ver 3 id duplicated error

Michal Seidl michal.seidl at gmail.com
Tue May 16 08:52:13 PDT 2023

we use POSTGIS="3.3.1 3786b21" and have problem with validation of GML 
geometry. The validator complains about duplicated "id" values in 
generated XML in MultiSuface and Polygon.

<gml:MultiSurface srsName="EPSG:4326" gml:id="1">
     <gml:Polygon gml:id="1">
          <gml:posList srsDimension="2">0 0 0 1 1 1 1 0 0 

We have not found definition for GML ver 3.1.1 but for 3.2.1 by this 

If a multigeometry (such as a MultiPoint or MultiSurface) is assigned a 
gml:id of (for example) parentid, to permit GML 3.2.1 schema-validity, 
each geometry that the multigeometry contains will be automatically 
assigned a gml:id of the form parentid.1, parentid.2, … in order.

Is it Postgis bug or difference between GML ver 3.1.1 and 3.2.1?

Thanks for help Michal S.

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