http://www.someserver.com/wfs.cgi?
SERVICE=WFS&
VERSION=1.1.0&
REQUEST=LockFeature&
LOCKACTION=ALL&
TYPENAME=INWATER_1M,BuiltUpA_1M&
FILTER=(<Filter xmlns:gml="http://www.opengis.net/gml"><Within><PropertyName>wkbGeom</PropertyName><gml:Envelope><gml:lowerCorner>10 10</gml:lowerCorner><gml:upperCorner>20 20</gml:upperCorner></gml:Envelope></Within></Filter>)(<Filter xmlns:gml="http://www.opengis.net/gml"><Within><PropertyName>wkbGeom</PropertyName><gml:Envelope><gml:lowerCorner>10 10</gml:lowerCorner><gml:upperCorner>20 20</gml:upperCorner></gml:Envelope></Within></Filter>)