/*
 * ENUM: SE_RS_Elevation_Select
 *
 *   This data type is used by a <Reference Surface> instance to
 *   specify exactly one element from a ray / surface intersection
 *   set, as follows.
 *
 *   The elevation resolution process for a <Location 2D> works
 *   like this. A given <Location 2D> corresponds to the (unique)
 *   ray which is:
 *   1. Normal to the surface of the SRF ellipsoid.
 *   2. Intersects the ellipsoid at the same horizontal
 *      coordinates as the <Location 2D>
 *   3. Extends below the surface of the ellipsoid to a depth
 *      equal the minor radius of the ellipsoid.
 *
 *   The intersection of this ray with the resolution surface
 *   defines the corresponding <Location 3D>.
 *
 *   The above assumes, however, that the ray/surface intersection
 *   set contains exactly one element. SE_RS_Elevation_Select
 *   is used, in the case when the intersection set contains more
 *   than one intersection element, to choose exactly one element
 *   from that set.
 */

Enumerant Notes

SE_RS_ELEV_SEL_CLOSEST_TO_ORM_CENTRE

 Use the point with the lowest elevation.

SE_RS_ELEV_SEL_CLOSEST_TO_VERTICAL_DATUM

 Use the point with smallest absolute z value.
 $$$ identifier - see SCR-sri-6

SE_RS_ELEV_SEL_HIGHEST

 Use the point with largest z value.