diff --git a/calma/CalmaRdcl.c b/calma/CalmaRdcl.c
index 28acae08..e69bb386 100644
--- a/calma/CalmaRdcl.c
+++ b/calma/CalmaRdcl.c
@@ -405,17 +405,18 @@ calmaParseStructure(filename)
      */
     if (CalmaFlattenUses && (!was_called) && (npaths < 10) && (nsrefs == 0))
     {
-	/* To-do:  If CDFLATGDS is already set, need to remove	*/
+	/* If CDFLATGDS is already set, may need to remove	*/
 	/* existing planes and free memory.			*/
 
-	if (cifReadCellDef->cd_flags & CDFLATGDS)
+	if ((cifReadCellDef->cd_client != (ClientData)CLIENTDEFAULT) &&
+		(cifReadCellDef->cd_flags & CDFLATGDS))
 	{
 	    Plane **cifplanes = (Plane **)cifReadCellDef->cd_client;
 	    int pNum;
 
             for (pNum = 0; pNum < MAXCIFRLAYERS; pNum++)
             {
-                if (cifplanes[pNum] != NULL)
+		if (cifplanes[pNum] != NULL)
                 {
                     DBFreePaintPlane(cifplanes[pNum]);
                     TiFreePlane(cifplanes[pNum]);
@@ -903,7 +904,8 @@ calmaElementSref(filename)
 
 	    for (pNum = 0; pNum < MAXCIFRLAYERS; pNum++)
 	    {
-		if (gdsplanes[pNum] != NULL)
+		if ((def->cd_client != (ClientData)CLIENTDEFAULT) &&
+			(gdsplanes[pNum] != NULL))
 		{
 		    gdsCopyRec.plane = cifCurReadPlanes[pNum];
 		    if (isArray)
diff --git a/database/DBlabel2.c b/database/DBlabel2.c
index 91c1908d..c060ac14 100644
--- a/database/DBlabel2.c
+++ b/database/DBlabel2.c
@@ -296,18 +296,25 @@ DBTreeFindUse(name, use, scx)
 	if ((def->cd_flags & CDAVAILABLE) == 0)
 	    (void) DBCellRead(def, (char *) NULL, TRUE, NULL);
 
-	/*
-	 * Pull off the next component of path up to but not including
-	 * any array subscripts.
-	 */
-	for (cp = name; *cp && *cp != '[' && *cp != '/'; cp++)
-	    /* Nothing */;
-	csave = *cp;
-	*cp = '\0';
 	he = HashLookOnly(&def->cd_idHash, name);
-	*cp = csave;
 	if (he == NULL || HashGetValue(he) == NULL)
-	    return;
+	{
+	    /*
+	     * Pull off the next component of path up to but not including
+	     * any array subscripts.
+	     * NOTE:  This should check the array bounds and only remove
+	     * array components that are expected, not array components
+	     * embedded in the name.
+	     */
+	    for (cp = name; *cp && *cp != '[' && *cp != '/'; cp++)
+		/* Nothing */;
+	    csave = *cp;
+	    *cp = '\0';
+	    he = HashLookOnly(&def->cd_idHash, name);
+	    *cp = csave;
+	    if (he == NULL || HashGetValue(he) == NULL)
+		return;
+	}
 	use = (CellUse *) HashGetValue(he);
 	def = use->cu_def;
 
diff --git a/database/DBprop.c b/database/DBprop.c
index c2ded840..85574435 100644
--- a/database/DBprop.c
+++ b/database/DBprop.c
@@ -66,6 +66,15 @@ DBPropPut(cellDef, name, value)
 	HashInit( (HashTable *) cellDef->cd_props, 8, 0);
     }
     htab = (HashTable *) cellDef->cd_props;
+
+    /* Special handling of FIXED_BBOX, which uses CDFIXEDBBOX as a quick lookup */
+    if (!strcmp(name, "FIXED_BBOX"))
+    {
+	if (value == (ClientData)NULL)
+	    cellDef->cd_flags &= ~CDFIXEDBBOX;
+	else
+	    cellDef->cd_flags |= CDFIXEDBBOX;
+    }
     
     entry = HashFind(htab, name);
     oldvalue = (char *)HashGetValue(entry);
@@ -202,4 +211,8 @@ DBPropClearAll(cellDef)
     HashKill(htab);
     freeMagic((char *) htab);
     cellDef->cd_props = (ClientData) NULL;
+
+    /* Since CDFIXEDBBOX requires a FIXED_BBOX property, clearing all	*/
+    /* properties necessarily means this flag must be clear.		*/
+    cellDef->cd_flags &= ~CDFIXEDBBOX;
 }
diff --git a/extract/ExtBasic.c b/extract/ExtBasic.c
index 89e32cb7..57f12df1 100644
--- a/extract/ExtBasic.c
+++ b/extract/ExtBasic.c
@@ -123,18 +123,6 @@ LinkedBoundary **extSpecialBounds;	/* Linked Boundary List */
 NodeRegion *glob_subsnode = NULL;	/* Global substrate node */
 NodeRegion *temp_subsnode = NULL;	/* Last subsnode found */
 
-/* Structure used for finding substrate connections on implicitly-defined
- * substrates
- */
-
-typedef struct TSD1
-{
-    bool found;		/* Set to 1 if a substrate connection was found */
-    Rect rtrans;	/* Rectangle of device */
-    Rect rhalo;		/* Search halo around device */
-    NodeRegion *nreg;	/* Closest substrate region within halo */
-} TransSubsData;
-
 #define	EDGENULL(r)	((r)->r_xbot > (r)->r_xtop || (r)->r_ybot > (r)->r_ytop)
 
 /* Forward declarations */
@@ -3396,9 +3384,11 @@ extFindNodes(def, clipArea, subonly)
 {
     int extNodeAreaFunc();
     int extSubsFunc();
+    int extSubsFunc2();
     FindRegion arg;
     int pNum, n;
     TileTypeBitMask subsTypesNonSpace;
+    bool space_is_substrate;
 
     /* Reset perimeter and area prior to node extraction */
     for (n = 0; n < ExtCurStyle->exts_numResistClasses; n++)
@@ -3418,19 +3408,52 @@ extFindNodes(def, clipArea, subonly)
     /* call extNodeAreaFunc() on the first of these to generate	 */
     /* a single substrate node.					 */
 
+    /* Refinement:  Split search into two parts, one on the	*/
+    /* globSubstratePlane and one on all other planes.  ONLY	*/
+    /* search other planes if TT_SPACE is in the list of	*/
+    /* substrate types, and then only consider those types to	*/
+    /* be part of the substrate node if they have only space	*/
+    /* below them on the globSubstratePlane.  This method lets	*/
+    /* a single type like "psd" operate on, for example, both	*/
+    /* the substrate and an isolated pwell, without implicitly	*/
+    /* connecting the isolated pwell to the substrate.		*/
+
     temp_subsnode = (NodeRegion *)NULL;		// Reset for new search
 
+    if (TTMaskHasType(&ExtCurStyle->exts_globSubstrateTypes, TT_SPACE))
+	space_is_substrate = True;
+    else
+	space_is_substrate = False;
+
     TTMaskZero(&subsTypesNonSpace);
     TTMaskSetMask(&subsTypesNonSpace, &ExtCurStyle->exts_globSubstrateTypes);
     TTMaskClearType(&subsTypesNonSpace, TT_SPACE);
 
+    pNum = ExtCurStyle->exts_globSubstratePlane;
+    /* Does the type set of this plane intersect the substrate types? */
+    if (TTMaskIntersect(&DBPlaneTypes[pNum], &subsTypesNonSpace))
+    {
+	arg.fra_pNum = pNum;
+	DBSrPaintClient((Tile *) NULL, def->cd_planes[pNum],
+			&TiPlaneRect, &subsTypesNonSpace, extUnInit,
+			extSubsFunc, (ClientData) &arg);
+    }
+
     for (pNum = PL_TECHDEPBASE; pNum < DBNumPlanes; pNum++)
     {
+	if (pNum == ExtCurStyle->exts_globSubstratePlane) continue;
+
 	/* Does the type set of this plane intersect the substrate types? */
+
 	if (TTMaskIntersect(&DBPlaneTypes[pNum], &subsTypesNonSpace))
 	{
 	    arg.fra_pNum = pNum;
-	    DBSrPaintClient((Tile *) NULL, def->cd_planes[pNum],
+	    if (space_is_substrate)
+		DBSrPaintClient((Tile *) NULL, def->cd_planes[pNum],
+			&TiPlaneRect, &subsTypesNonSpace, extUnInit,
+			extSubsFunc2, (ClientData) &arg);
+	    else
+		DBSrPaintClient((Tile *) NULL, def->cd_planes[pNum],
 			&TiPlaneRect, &subsTypesNonSpace, extUnInit,
 			extSubsFunc, (ClientData) &arg);
 	}
@@ -3503,6 +3526,39 @@ extSubsFunc(tile, arg)
     return (0);
 }
 
+int
+extSubsFunc2(tile, arg)
+    Tile *tile;
+    FindRegion *arg;
+{
+    int pNum; 
+    Rect tileArea;
+    int extSubsFunc3();
+
+    TiToRect(tile, &tileArea);
+
+    /* Run second search in the area of the tile on the substrate plane	*/
+    /* to make sure that nothing but space is under these tiles.	*/
+
+    pNum = ExtCurStyle->exts_globSubstratePlane;
+
+    if (DBSrPaintArea((Tile *) NULL, arg->fra_def->cd_planes[pNum],
+		&tileArea, &DBAllButSpaceBits, 
+		extSubsFunc3, (ClientData)NULL) == 0)
+    {
+	/* Mark this tile as pending and push it */
+	PUSHTILE(tile, arg->fra_pNum);
+    }
+    return (0);
+}
+
+int
+extSubsFunc3(tile)
+    Tile *tile;
+{
+    /* Stops the search because something that was not space was found */
+    return 1;
+}
 
 int
 extNodeAreaFunc(tile, arg)