The gml:minimumValue and gml:maximumValue properties allow the specification of
minimum and maximum value normally allowed for this axis, in the unit of measure for the
axis. For a continuous angular axis such as longitude, the values wrap-around at this value.
Also, values beyond this minimum/maximum can be used for specified purposes, such as in a
bounding box. A value of minus infinity shall be allowed for the gml:minimumValue element, a
value of plus infiniy for the gml:maximumValue element. If these elements are omitted, the
value is unspecified.