The nested elements of this filter must be specify a set of stations that are the conjunction of the final results This type can support N-dimensional bounds and arbitrary coordinate reference systems (CRS). The upperCorner and lowerCorner elements support a space separated list of double values representing the coordinates in the specified CRS (specified via the srsName attribute). Using a fake CRS of "lat [deg]/lon [deg]/elevation [m]" one could specify a 3-dimensional cube with length .9 degrees with 1.8 degrees, depth 500 meters (extending 100 meters below sea level) as: 60.1 30.2 -100 61.0 32.0 400