typedef enum {
	MPIPathElementTypeINVALID,

	MPIPathElementTypeARC,  /* only 2D */
	MPIPathElementTypeARC_CENTER,  /* only 2D */
	MPIPathElementTypeARC_END_POINT, /* both 2D and 3D */
	MPIPathElementTypeHELIX, /* not currently supported */
	MPIPathElementTypeIO, /* not currently supported */
	MPIPathElementTypeLINE, /* both 2D and 3D */

	MPIPathElementTypeMASK,
} MPIPathElementType;