code: function( minx, miny, maxx, maxy ) {
  		var bbox = '';
  		if ( this.version === '1.3.0' ) {
  			bbox = [minx, miny, maxx, maxy].join( ',' );
  		} else {
  			bbox = [miny, minx, maxy, maxx].join( ',' );
  		}
  		return bbox;
  	}
docs: Returns a bbox WMS string.
  @param {Float} minx left  bound of the bounding box in CRS units
  @param {Float} miny lower bound of the bounding box in CRUS units
  @param {Float} maxx right bound of the bounding box in CRUS units
  @param {Float} maxy upper bound of the bounding box in CRUS units