Syntax

   @GMLGeometry(TO_ATTRIBUTE, <gml version>, <attrName>, <omit namespace declaration>, <prefer polygon over surfaces>, <srs name>, <srs axis order>)
   @GMLGeometry(FROM_ATTRIBUTE, <attrName>[, <axisOrder>])
   
Arguments

   <command>
      Specifies the action to be taken, TO_ATTRIBUTE exports the geometry from 
      the feature into an attribute, while FROM_ATTRIBUTE imports the GML 
      geometry from an attribute into the feature.

      Range: TO_ATTRIBUTE | FROM_ATTRIBUTE
   
   <gml version>
      The GML version in which the geometry will be written.
      
      Range: GML_2.1.2 | GML_3.1.1 | GML_3.2.1
         
   <axisOrder>    
      Forces the GML coordinates in the <gml:pos> and <gml:posList> elements to 
      be interpreted in the specified axis order.

      Range: xy | yx | xyz | yxz
         
   <attrName>
      The name of the attribute to have the geometry saved.
      
      Range: String
                   
Description

   This command is used to serialize and de-serialize a feature's geometry into 
   and from GML. The <gml version> string indicates the type of GML to write, 
   currently only GML 2.1.2, GML 3.1.1 and GML 3.2.1 are supported.  
   
   The gml:id XML attribute is required in GML 3.2.1, to create a valid GML 
   3.2.1 geometry fragment, the function must populate the gml:id attributes. 
   The values for the gml:id attributes are either taken directly from the 
   corresponding "gml_id" geometry trait, or generated indirectly from the 
   feature's "gml_id" attribute, or indirectly from a "uuid", in the case the 
   feature is lacking a "gml_id" attribute. 
   
      Note: In TO_ATTRIBUTE mode, if the feature has no geometry, then the 
      resulting attribute will have a blank value.