A defined volume in the air, described as a horizontal projection with vertical limits.<br /></p><p><br /></p><p>This class is a modified version of the AIXM AirspaceVolume class.  This version of the class has been reduced to horizontal and vertical geographic information, and the horizontal geometry was broadened to allow a horizontal description of airspace using any geometric primitive in combination with an upper and lower vertical limit.<br /></p><p><br /></p><p><font color="#ff0000">The use of GM_Primitive may not be ideal.  This was generalized to allow for 3-dimensional descriptions using ArcByCentrePoint, Surface, or other planar geometries that can be combined with vertical limits to describe a full 3-D solid.  Is there a better GM_* sub-type that would serve better here?</font><br /></p><p><br /></p><p>References from the original AIXM class to AIXM data types were replaced with the closest ISO equivalents.  Specifically, ValDistanceVertical (for upper and lower limit) were replaced with Measure. Instances of the AIXM Surface were replaced with GM_Primitive.<br /></p><p><br /></p><p>The horizontal components may be any 2-dimensional geometry, such as an ArcByCentrePoint or a Polygon.  In conjunction with upper and lower limits this describes a 3-dimensional shape and is equivalent to GM_Solid.  <br /></p><p><br /></p><p>When the upper limit is missing, this indicates that the described area extends to the maximum height above the earth that is significant to aviation.  When the lower limit is missing, this indicates that the described area extends down to ground level.<br /></p>