/*
 * ENUM: SRM_Up_Direction
 *
 *   This data type is used to define the LSR Spatial Reference Frame.
 *   Used when defining LSR spatial reference frame parameters,
 *   to specify which axis within the LSR SRF will, when
 *   transformed into a non-LSR SRF, be tied to that SRF's
 *   "up" axis.
 *
 *   Note that this axis shall be chosen so that it is
 *   perpendicular to the axis specified as the "forward"
 *   axis.
 *
 *   For example, when an LSR SRF is transformed into a
 *   Mercator reference frame, the LSR "up" axis is
 *   transformed so that it aligns with the positive
 *   z axis of the Mercator SRF.
 */