Index: hid_cam.c
===================================================================
--- hid_cam.c	(revision 19419)
+++ hid_cam.c	(revision 19420)
@@ -203,6 +203,74 @@
 	return 0;
 }
 
+static char *lp_err = "";
+
+/* Parse a layer directive: split at comma, curr will end up holding the
+   layer name. If there were transformations in (), they are split and
+   listed in tr up to at most *trc entries. Returns NULL on error or
+   pointer to the next layer directive. */
+static char *parse_layer(char *curr, char **trk, char **trv, int *trc)
+{
+	char *s, *lasta, *eq;
+	int level = 0, trmax = *trc;
+	*trc = 0;
+
+	for(s = curr; *s != '\0'; s++) {
+		switch(*s) {
+			case '(':
+				if (level == 0) {
+					*s = '\0';
+					lasta = s+1;
+				}
+				level++;
+				break;
+			case ')':
+				if (level > 0)
+					level--;
+				if (level == 0)
+					goto append;
+				break;
+			case ',':
+				if (level == 0)
+					goto out;
+				append:;
+				if (*trc >= trmax)
+					return lp_err;
+				lasta = strip(lasta);
+				trk[*trc] = lasta;
+				eq = strchr(lasta, '=');
+				if (eq != NULL) {
+					*eq = '\0';
+					eq++;
+				}
+				trv[*trc] = eq;
+				(*trc)++;
+				*s = '\0';
+				lasta = s+1;
+		}
+	}
+
+	if (level > 0)
+		return lp_err;
+
+	out:;
+
+	if (*s != '\0') {
+		*s = '\0';
+		s++;
+		return s;
+	}
+
+	return NULL; /* no more layers */
+}
+
+static void parse_layer_args(char **trk, char **trv, int trc)
+{
+	int n;
+	for(n = 0; n < trc; n++)
+		pcb_trace(" [%d] '%s' '%s'\n", n, trk[n], trv[n]);
+}
+
 int pcb_cam_begin(pcb_board_t *pcb, pcb_cam_t *dst, const char *src, const pcb_hid_attribute_t *attr_tbl, int numa, pcb_hid_attr_val_t *options)
 {
 	char *curr, *next;
@@ -226,7 +294,6 @@
 	*next = '\0';
 	next++;
 	dst->fn = strip(dst->inst);
-pcb_trace("CAM FN='%s'\n", dst->fn);
 
 	while(isspace(*next))
 		next++;
@@ -233,12 +300,17 @@
 
 	/* parse layers */
 	for(curr = next; curr != NULL; curr = next) {
+		char *trk[64], *trv[64];
+		int trc = sizeof(trk) / sizeof(trk[0]);
+		next = parse_layer(curr, trk, trv, &trc);
+		if (next == lp_err) {
+			pcb_message(PCB_MSG_ERROR, "CAM rule: invalid layer transformation\n");
+			goto err;
+		}
 
-		next = strchr(curr, ',');
-		if (next != NULL) {
-			*next = '\0';
-			next++;
-		}
+{
+}
+
 		curr = strip(curr);
 		if (*curr == '@') {
 			/* named layer */
@@ -264,6 +336,8 @@
 				goto err;
 
 #warning TODO: extend the syntax for purpose
+			parse_layer_args(trk, trv, trc);
+
 			vl = pcb_vlayer_get_first(lyt, NULL, -1);
 			if (vl == NULL) {
 				pcb_layergrp_id_t gids[PCB_MAX_LAYERGRP];