Index: read.c
===================================================================
--- read.c	(revision 28991)
+++ read.c	(revision 28992)
@@ -644,7 +644,6 @@
 		return 0;
 
 	if (strcmp(tmp->argv[1], "MNT_SIDE") == 0) {
-TODO("Look how opposite side to MNT_SIDE is defined.\n");
 		if (subc_side != 0) {
 			*side = subc_side;
 			if ((subc_side & PCB_LYT_TOP) != 0)
@@ -656,6 +655,18 @@
 		else
 			hkp_error(n, "Unknown MNT_SIDE while parsing package.\n");
 	}
+	if (strcmp(tmp->argv[1], "OPP_SIDE") == 0) {
+		if (subc_side != 0) {
+			*side = (subc_side ^ PCB_LYT_TOP) ^ PCB_LYT_BOTTOM;
+			if ((subc_side & PCB_LYT_TOP) != 0)
+				lyname = lyname_bottom;
+			else
+				lyname = lyname_top;
+			return 1;
+		}
+		else
+			hkp_error(n, "Unknown MNT_SIDE while parsing package.\n");
+	}
 	else if (strcmp(tmp->argv[1], "TOP") == 0) {
 		*side = PCB_LYT_TOP;
 		lyname = lyname_top;