The ST_EnvelopeFromGML() function
The ST_EnvelopeFromGML() function takes a GML2 or GML3 string representation of an envelope and an optional spatial reference ID and returns a geometry object.
If the srsName attribute is specified in the GML string, then a corresponding entry in the spatial_references table must exist unless it is specified as UNKNOWN or DEFAULT.
Syntax
ST_EnvelopeFromGML(gml_string lvarchar)
ST_EnvelopeFromGML(gml_string lvarchar, SRID integer)
Return type
A four sided ST_Polygon representing the envelope.
Example
ST_EnvelopeFromGML('<gml:Envelope>
<gml:lowerCorner> -180.0 -90.0</gml:lowerCorner>
<gml:upperCorner> 180.0 90.0 </gml:upperCorner>
</gml:Envelope>', 1003)