NULL_EXPRESSION   289 create.c           exp = crb_alloc_expression(NULL_EXPRESSION);
NULL_EXPRESSION   302 eval.c             case NULL_EXPRESSION:	/* FALLTHRU */
NULL_EXPRESSION   378 eval.c             case NULL_EXPRESSION:		/* FALLTHRU */
NULL_EXPRESSION   869 eval.c             case NULL_EXPRESSION:
NULL_EXPRESSION   171 util.c             case NULL_EXPRESSION:	/* FALLTHRU */