/*
 * STRUCT: SRM_GC_3D_PARAMETERS
 *
 *   No parameters are needed to define the Geocentric (GC) 3D
 *   SRF, but a struct is declared for it anyway, to parallel the
 *   struct definitions of the other SRFs. The associated ORM/ERM
 *   is defined by the WGS-84 ellipsoid and mass-center.
 */