Index: trunk/src/netlist.c
===================================================================
--- trunk/src/netlist.c	(revision 29117)
+++ trunk/src/netlist.c	(revision 29118)
@@ -951,7 +951,7 @@
 	new_len = pcb_termlist_length(&target_net->conns);
 	if (new_len != old_len) {
 		id = pcb_concat(sc1->refdes, "-", o1->term, NULL);
-		pcb_ratspatch_append(pcb, RATP_ADD_CONN, id, target_net->name, NULL);
+		pcb_ratspatch_append(pcb, RATP_ADD_CONN, id, target_net->name, NULL, 1);
 		free(id);
 	}
 
@@ -960,7 +960,7 @@
 	new_len = pcb_termlist_length(&target_net->conns);
 	if (new_len != old_len) {
 		id = pcb_concat(sc2->refdes, "-", o2->term, NULL);
-		pcb_ratspatch_append(pcb, RATP_ADD_CONN, id, target_net->name, NULL);
+		pcb_ratspatch_append(pcb, RATP_ADD_CONN, id, target_net->name, NULL, 1);
 		free(id);
 	}
 
Index: trunk/src/rats_patch.c
===================================================================
--- trunk/src/rats_patch.c	(revision 29117)
+++ trunk/src/rats_patch.c	(revision 29118)
@@ -48,7 +48,17 @@
 	"edited"
 };
 
-void pcb_ratspatch_append(pcb_board_t *pcb, pcb_rats_patch_op_t op, const char *id, const char *a1, const char *a2)
+/*** undoable ratspatch append */
+
+typedef struct {
+	pcb_board_t *pcb;
+	pcb_rats_patch_op_t op;
+	char *id;
+	char *a1;
+	char *a2;
+} pcb_ratspatch_append_t;
+
+static void pcb_ratspatch_append_(pcb_board_t *pcb, pcb_rats_patch_op_t op, const char *id, const char *a1, const char *a2)
 {
 	pcb_ratspatch_line_t *n;
 
@@ -73,6 +83,11 @@
 	n->next = NULL;
 }
 
+void pcb_ratspatch_append(pcb_board_t *pcb, pcb_rats_patch_op_t op, const char *id, const char *a1, const char *a2, int undoable)
+{
+	pcb_ratspatch_append_(pcb, op, id, a1, a2);
+}
+
 static void rats_patch_free_fields(pcb_ratspatch_line_t *n)
 {
 	if (n->id != NULL)
@@ -131,7 +146,7 @@
 	}
 
 quit:;
-	pcb_ratspatch_append(pcb, op, id, a1, a2);
+	pcb_ratspatch_append(pcb, op, id, a1, a2, 0);
 }
 
 /* Unlink n from the list; if do_free is non-zero, also free fields and n */
Index: trunk/src/rats_patch.h
===================================================================
--- trunk/src/rats_patch.h	(revision 29117)
+++ trunk/src/rats_patch.h	(revision 29118)
@@ -56,7 +56,7 @@
 const char *pcb_netlist_names[PCB_NUM_NETLISTS];
 
 /* Allocate and append a patch line to the patch list */
-void pcb_ratspatch_append(pcb_board_t *pcb, pcb_rats_patch_op_t op, const char *id, const char *a1, const char *a2);
+void pcb_ratspatch_append(pcb_board_t *pcb, pcb_rats_patch_op_t op, const char *id, const char *a1, const char *a2, int undoable);
 
 /* Free the patch list and all memory claimed by patch list items */
 void pcb_ratspatch_destroy(pcb_board_t *pcb);
Index: trunk/src_plugins/io_lihata/read.c
===================================================================
--- trunk/src_plugins/io_lihata/read.c	(revision 29117)
+++ trunk/src_plugins/io_lihata/read.c	(revision 29118)
@@ -2175,13 +2175,13 @@
 			nval = lht_dom_hash_get(np, "term");
 			if ((nval == NULL) || (nval->type != LHT_TEXT) || (*nval->data.text.value == '\0'))
 				return iolht_error(nval, "netlist patch terminal ID must be a non-empty string (del_conn)\n");
-			pcb_ratspatch_append(pcb, RATP_DEL_CONN, nval->data.text.value, nnet->data.text.value, NULL);
+			pcb_ratspatch_append(pcb, RATP_DEL_CONN, nval->data.text.value, nnet->data.text.value, NULL, 0);
 		}
 		else if (strcmp(np->name, "add_conn") == 0) {
 			nval = lht_dom_hash_get(np, "term");
 			if ((nval == NULL) || (nval->type != LHT_TEXT) || (*nval->data.text.value == '\0'))
 				return iolht_error(nval, "netlist patch terminal ID must be a non-empty string (add_conn)\n");
-			pcb_ratspatch_append(pcb, RATP_ADD_CONN, nval->data.text.value, nnet->data.text.value, NULL);
+			pcb_ratspatch_append(pcb, RATP_ADD_CONN, nval->data.text.value, nnet->data.text.value, NULL, 0);
 		}
 		else if (strcmp(np->name, "change_attrib") == 0) {
 			nkey = lht_dom_hash_get(np, "key");
@@ -2190,7 +2190,7 @@
 			nval = lht_dom_hash_get(np, "val");
 			if ((nval == NULL) || (nval->type != LHT_TEXT))
 				return iolht_error(nval, "netlist patch attrib value must be a non-empty string (change_attrib)\n");
-			pcb_ratspatch_append(pcb, RATP_CHANGE_ATTRIB, nnet->data.text.value, nkey->data.text.value, nval->data.text.value);
+			pcb_ratspatch_append(pcb, RATP_CHANGE_ATTRIB, nnet->data.text.value, nkey->data.text.value, nval->data.text.value, 0);
 		}
 	}
 	return 0;
Index: trunk/src_plugins/io_pcb/parse_y.c
===================================================================
--- trunk/src_plugins/io_pcb/parse_y.c	(revision 29117)
+++ trunk/src_plugins/io_pcb/parse_y.c	(revision 29118)
@@ -2910,19 +2910,19 @@
 
   case 197:
 #line 1315 "parse_y.y" /* yacc.c:1652  */
-    { pcb_ratspatch_append(yyPCB, RATP_ADD_CONN, (yyvsp[-2].string), (yyvsp[-1].string), NULL); free((yyvsp[-2].string)); free((yyvsp[-1].string)); }
+    { pcb_ratspatch_append(yyPCB, RATP_ADD_CONN, (yyvsp[-2].string), (yyvsp[-1].string), NULL, 0); free((yyvsp[-2].string)); free((yyvsp[-1].string)); }
 #line 2915 "parse_y.c" /* yacc.c:1652  */
     break;
 
   case 198:
 #line 1316 "parse_y.y" /* yacc.c:1652  */
-    { pcb_ratspatch_append(yyPCB, RATP_DEL_CONN, (yyvsp[-2].string), (yyvsp[-1].string), NULL); free((yyvsp[-2].string)); free((yyvsp[-1].string)); }
+    { pcb_ratspatch_append(yyPCB, RATP_DEL_CONN, (yyvsp[-2].string), (yyvsp[-1].string), NULL, 0); free((yyvsp[-2].string)); free((yyvsp[-1].string)); }
 #line 2921 "parse_y.c" /* yacc.c:1652  */
     break;
 
   case 199:
 #line 1317 "parse_y.y" /* yacc.c:1652  */
-    { pcb_ratspatch_append(yyPCB, RATP_CHANGE_ATTRIB, (yyvsp[-3].string), (yyvsp[-2].string), (yyvsp[-1].string)); free((yyvsp[-3].string)); free((yyvsp[-2].string)); free((yyvsp[-1].string)); }
+    { pcb_ratspatch_append(yyPCB, RATP_CHANGE_ATTRIB, (yyvsp[-3].string), (yyvsp[-2].string), (yyvsp[-1].string), 0); free((yyvsp[-3].string)); free((yyvsp[-2].string)); free((yyvsp[-1].string)); }
 #line 2927 "parse_y.c" /* yacc.c:1652  */
     break;
 
Index: trunk/src_plugins/io_pcb/parse_y.y
===================================================================
--- trunk/src_plugins/io_pcb/parse_y.y	(revision 29117)
+++ trunk/src_plugins/io_pcb/parse_y.y	(revision 29118)
@@ -1312,9 +1312,9 @@
 
 netpatch
 			/* name style pin pin ... */
-		: T_ADD_CONN      '(' STRING STRING ')'         { pcb_ratspatch_append(yyPCB, RATP_ADD_CONN, $3, $4, NULL); free($3); free($4); }
-		| T_DEL_CONN      '(' STRING STRING ')'         { pcb_ratspatch_append(yyPCB, RATP_DEL_CONN, $3, $4, NULL); free($3); free($4); }
-		| T_CHANGE_ATTRIB '(' STRING STRING STRING ')'  { pcb_ratspatch_append(yyPCB, RATP_CHANGE_ATTRIB, $3, $4, $5); free($3); free($4); free($5); }
+		: T_ADD_CONN      '(' STRING STRING ')'         { pcb_ratspatch_append(yyPCB, RATP_ADD_CONN, $3, $4, NULL, 0); free($3); free($4); }
+		| T_DEL_CONN      '(' STRING STRING ')'         { pcb_ratspatch_append(yyPCB, RATP_DEL_CONN, $3, $4, NULL, 0); free($3); free($4); }
+		| T_CHANGE_ATTRIB '(' STRING STRING STRING ')'  { pcb_ratspatch_append(yyPCB, RATP_CHANGE_ATTRIB, $3, $4, $5, 0); free($3); free($4); free($5); }
 		;
 
 attribute