--- ray/src/common/caldefn.c	2019/12/28 18:05:13	2.27
+++ ray/src/common/caldefn.c	2022/03/12 15:50:13	2.30
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: caldefn.c,v 2.27 2019/12/28 18:05:13 greg Exp $";
+static const char	RCSid[] = "$Id: caldefn.c,v 2.30 2022/03/12 15:50:13 greg Exp $";
 #endif
 /*
  *  Store variable definitions.
@@ -196,13 +196,15 @@ dremove(			/* delete all definitions of name */
 
 
 int
-vardefined(	/* return non-zero if variable defined */
+vardefined(	/* return '=' or ':' if variable/constant defined */
 	char  *name
 )
 {
     EPNODE  *dp;
 
-    return((dp = dlookup(name)) != NULL && dp->v.kid->type == SYM);
+    if ((dp = dlookup(name)) == NULL || dp->v.kid->type != SYM)
+    	return(0);
+    return(dp->type);
 }
 
 
@@ -637,6 +639,8 @@ getdefn(void)
 	    ep2 = newnode();
 	    ep2->type = SYM;
 	    ep2->v.name = savestr(getname());
+	    if (strchr(ep2->v.name, CNTXMARK) != NULL)
+		syntax("illegal parameter name");
 	    addekid(ep1, ep2);
 	} while (nextc == ',');
 	if (nextc != ')')
@@ -702,7 +706,7 @@ getchan(void)			/* A -> $N = E1 */
 
 
 static double			/* evaluate a variable */
-dvalue(char  *name, EPNODE	*d)
+dvalue(char *name, EPNODE *d)
 {
     EPNODE  *ep1, *ep2;
     
@@ -714,6 +718,10 @@ dvalue(char  *name, EPNODE	*d)
     ep1 = d->v.kid->sibling;			/* get expression */
     if (ep1->type == NUM)
 	return(ep1->v.num);			/* return if number */
+    if (esupport&E_RCONST && d->type == ':') {
+	wputs(name);
+	wputs(": assigned non-constant value\n");
+    }
     ep2 = ep1->sibling;				/* check time */
     if (eclock >= MAXCLOCK)
 	eclock = 1;				/* wrap clock counter */