A gml:CircleByCenterPoint is an gml:ArcByCenterPoint with identical start and end angle to form a full circle. Again, this representation can be used only in 2D.
<element name="CircleByCenterPoint" type="gml:CircleByCenterPointType" substitutionGroup="gml:ArcByCenterPoint"><annotation><documentation>A gml:CircleByCenterPoint is an gml:ArcByCenterPoint with identical start and end angle to form a full circle. Again, this representation can be used only in 2D.</documentation></annotation></element>