diff --git a/VERSION b/VERSION
index d898cef..6b03f2a 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.5.297
+1.5.298
diff --git a/base/netcmp.c b/base/netcmp.c
index dfa3359..6fe8af5 100644
--- a/base/netcmp.c
+++ b/base/netcmp.c
@@ -8481,6 +8481,182 @@ int EquivalentElement(char *name, struct nlist *circuit, struct objlist **retobj
   return retval;
 }
 
+/*------------------------------------------------------*/
+/* Structure and definitins used by derivedprops()	*/
+/*------------------------------------------------------*/
+
+enum DerivedType {area_type, perimeter_type};
+
+typedef struct _derivedpropdata {
+    struct nlist *cell;
+    int fnum;
+    char *pwidth;
+    char *plength;
+    enum DerivedType type;
+} DerivedPropData;
+
+/*------------------------------------------------------*/
+/* derivedprops --- Callback function for a recursive	*/
+/* search over all cells with a pointer clientdata.	*/
+/* The pointer is a DerivedPropData structure that	*/
+/* contains the information needed to determine how to	*/
+/* generate an "area" or "perimeter" property based on	*/
+/* the device length and width.				*/
+/*------------------------------------------------------*/
+
+struct nlist *derivedprops(struct hashlist *p, void *clientdata)
+{
+    struct nlist *ptr;
+    struct objlist *ob;
+    struct valuelist *vl, *newvlist;
+    struct nlist *tc;
+    struct property *prop;
+    int i;
+    double valuew, valuel, valuea = 0.0, valuep = 0.0;
+    int haswidth = FALSE, haslength = FALSE;
+    int hasarea = FALSE, hasperimeter = FALSE;
+
+    DerivedPropData *dpd = (DerivedPropData *)clientdata;
+
+    tc = dpd->cell;
+    ptr = (struct nlist *)(p->ptr);
+    if (ptr->file != tc->file) return NULL;
+
+    /* Search all instances in the cell for properties, find those matching
+     * the cell class to be modified, and create a new derived property for
+     * area or perimeter for that instance.
+     */
+
+    for (ob = ptr->cell; ob; ob = ob->next) {
+       if (ob->type == PROPERTY) {
+	  if ((*matchfunc)(ob->model.class, tc->name)) {
+	     for (i = 0;; i++) {
+		vl = &(ob->instance.props[i]);
+		if (vl->type == PROP_ENDLIST) break;
+		prop = (struct property *)HashLookup(vl->key, &(tc->propdict));
+		if (prop != NULL) {
+		    if ((*matchfunc)(vl->key, dpd->pwidth)) {
+			haswidth = TRUE;
+			if (vl->type == PROP_DOUBLE)
+			    valuew = vl->value.dval;
+			else if (vl->type == PROP_INTEGER)
+			    valuew = (double)vl->value.ival;
+			else
+			   haswidth = FALSE;
+		    }
+		    else if ((*matchfunc)(vl->key, dpd->plength)) {
+			haslength = TRUE;
+			if (vl->type == PROP_DOUBLE)
+			    valuel = vl->value.dval;
+			else if (vl->type == PROP_INTEGER)
+			    valuel = (double)vl->value.ival;
+			else
+			    haslength = FALSE;
+		    }
+		    else if ((dpd->type == area_type)
+				&& ((*matchfunc)(vl->key, "area"))) {
+			hasarea = TRUE;
+		    }
+		    else if ((dpd->type == perimeter_type)
+				&& ((*matchfunc)(vl->key, "perimeter"))) {
+			hasperimeter = TRUE;
+		    }
+		}
+	     }
+	     if (haslength && haswidth) {
+
+		/* Once the property names for device width and length have
+		 * been found, and the values recorded, add the area or
+		 * perimeter value to the property list for the instance,
+		 * unless the instance already has the property.
+		 */
+		newvlist = (struct valuelist *)CALLOC(i + 1, sizeof(struct valuelist));
+		vl = &newvlist[i];
+		vl->key = NULL;
+		vl->type = PROP_ENDLIST;
+		vl->value.ival = 0;
+
+		vl = &newvlist[--i];
+		if ((dpd->type == area_type) && (!hasarea)) {
+		    valuea = valuew * valuel;
+		    vl->key = strsave("area");
+		    vl->type = PROP_DOUBLE;
+		    vl->value.dval = valuea;
+			
+		} else if ((dpd->type == perimeter_type) && (!hasperimeter)) {
+		    valuep = 2 * (valuew + valuel);
+		    vl->key = strsave("perimeter");
+		    vl->type = PROP_DOUBLE;
+		    vl->value.dval = valuep;
+		}
+		for (--i; i >= 0; i--) {
+		   vl = &newvlist[i];
+		   vl->key = ob->instance.props[i].key;
+		   vl->type = ob->instance.props[i].type;
+		   vl->value = ob->instance.props[i].value;
+		}
+		FREE(ob->instance.props);
+		ob->instance.props = newvlist;
+	     }
+	  }
+       }
+    }
+}
+
+/*------------------------------------------------------*/
+/* Create a new "area" or "perimeter" property in all	*/
+/* instances of a given device, based on the specified	*/
+/* names for the width and length parameters.		*/
+/*------------------------------------------------------*/
+
+void
+DeriveProperty(struct nlist *tc, int fnum, char *pwidth, char *plength, 
+	enum DerivedType type)
+{
+    DerivedPropData dpd;
+
+    dpd.pwidth = pwidth;
+    dpd.plength = plength;
+    dpd.fnum = fnum;
+    dpd.cell = tc;
+    dpd.type = type;
+
+    /* Create the new derived property in the cell. */
+    if (type == area_type)
+	PropertyDouble(tc->name, fnum, "area", 0.01, 0.0);    
+    else if (type == perimeter_type)
+	PropertyDouble(tc->name, fnum, "perimeter", 0.01, 0.0);    
+    else
+	return;
+
+    /* Find all instances of the cell and add the derived property */
+    RecurseCellHashTable2(derivedprops, (void *)(&dpd));
+}
+
+/*------------------------------------------------------*/
+/* Create a new "area" property in all instances of a	*/
+/* given device, based on the specified width and	*/
+/* length parameter names.				*/
+/*------------------------------------------------------*/
+
+void
+DeriveAreaProperty(struct nlist *tp, int fnum, char *pwidth, char *plength)
+{
+    DeriveProperty(tp, fnum, pwidth, plength, area_type);
+}
+
+/*------------------------------------------------------*/
+/* Create a new "perimeter" property in all instances	*/
+/* of a given device, based on the specified width and	*/
+/* length parameter names.				*/
+/*------------------------------------------------------*/
+
+void
+DerivePerimeterProperty(struct nlist *tp, int fnum, char *pwidth, char *plength)
+{
+    DeriveProperty(tp, fnum, pwidth, plength, perimeter_type);
+}
+
 /*------------------------------------------------------*/
 /* Flatten the two cells at the top of the compare	*/
 /* queue.						*/
diff --git a/base/netcmp.h b/base/netcmp.h
index 6d90178..a0f646a 100644
--- a/base/netcmp.h
+++ b/base/netcmp.h
@@ -70,6 +70,8 @@ extern int remove_group_tags(struct objlist *ob);
 #ifdef TCL_NETGEN
 extern int EquivalentNode();
 extern int EquivalentElement();
+extern void DeriveAreaProperty();
+extern void DerivePerimeterProperty();
 
 extern void enable_interrupt();
 extern void disable_interrupt();
diff --git a/tcltk/netgen.tcl.in b/tcltk/netgen.tcl.in
index 2d5c13c..c413f44 100644
--- a/tcltk/netgen.tcl.in
+++ b/tcltk/netgen.tcl.in
@@ -594,6 +594,9 @@ proc netgen::lvs { name1 name2 {setupfile setup.tcl} {logfile comp.out} args} {
 	    lappend properr [lindex $endval 0]
 	 } elseif {$uresult == -2} {	;# unmatched pins
 	    set doCheckFlatten 1
+	 } elseif {$uresult == -4} {	;# unmatched pins and properties
+	    lappend properr [lindex $endval 0]
+	    set doCheckFlatten 1
 	 }
       } else {
 	 # not equivalent
diff --git a/tcltk/tclnetgen.c b/tcltk/tclnetgen.c
index 5071a02..04274f6 100644
--- a/tcltk/tclnetgen.c
+++ b/tcltk/tclnetgen.c
@@ -2572,6 +2572,7 @@ _netcmp_run(ClientData clientData,
 /*	 0: not verified				*/
 /*	-1: no elements or nodes			*/
 /*	-3: verified with property error		*/
+/*	-4: verified with property and port errors	*/
 /*   equiv option					*/
 /*	-2: pin mismatch				*/
 /*							*/
@@ -2673,8 +2674,12 @@ _netcmp_verify(ClientData clientData,
       else if (automorphisms == -2) {
 	 if (index == EQUIV_IDX)
 	    Tcl_SetObjResult(interp, Tcl_NewBooleanObj(1));
-	 else if (index == UNIQUE_IDX)
-	    Tcl_SetObjResult(interp, Tcl_NewIntObj(-2));
+	 else if (index == UNIQUE_IDX) {
+	    if (PropertyErrorDetected == 0)
+	       Tcl_SetObjResult(interp, Tcl_NewIntObj(-2));
+	    else
+	       Tcl_SetObjResult(interp, Tcl_NewIntObj(-4));
+	 }
 	 else if (index > 0)
 	    Fprintf(stdout, "Circuits match uniquely with port errors.\n");
       }
@@ -3428,13 +3433,21 @@ _netcmp_property(ClientData clientData,
     double dval;
     int ival, argstart;
 
+    char *topoptions[] = {
+	"default", "series", "serial", "parallel", "topology", NULL
+    };
+    enum TopOptionIdx {
+	TOP_DEFAULT_IDX, TOP_SERIES_IDX, TOP_SERIAL_IDX, TOP_PARALLEL_IDX,
+	TOP_TOPOLOGY_IDX
+    };
+
     char *options[] = {
 	"add", "create", "remove", "delete", "tolerance", "merge", "serial",
-	"series", "parallel", "associate", "topology", NULL
+	"series", "parallel", "associate", "derive", NULL
     };
     enum OptionIdx {
 	ADD_IDX, CREATE_IDX, REMOVE_IDX, DELETE_IDX, TOLERANCE_IDX, MERGE_IDX,
-	SERIAL_IDX, SERIES_IDX, PARALLEL_IDX, ASSOCIATE_IDX, TOPOLOGY_IDX
+	SERIAL_IDX, SERIES_IDX, PARALLEL_IDX, ASSOCIATE_IDX, DERIVE_IDX
     };
     int result, index, idx2;
 
@@ -3469,6 +3482,14 @@ _netcmp_property(ClientData clientData,
 	COMB_NONE_IDX, COMB_PAR_IDX, COMB_ADD_IDX, COMB_CRITICAL_IDX
     };
 
+    char *deriveoptions[] = {
+	"area", "perimeter", NULL
+    };
+
+    enum DeriveOptionIdx {
+	AREA_IDX, PERIMETER_IDX
+    };
+
     char *yesno[] = {
 	"on", "yes", "true", "enable", "allow",
 	"off", "no", "false", "disable", "prohibit", NULL
@@ -3483,8 +3504,13 @@ _netcmp_property(ClientData clientData,
 	"strict", "relaxed", NULL
     };
 
+    /* Don't need to check return value */
+    index = -1;
+    Tcl_GetIndexFromObj(interp, objv[1], (CONST84 char **)topoptions,
+		"option", 0, &index);
+
     /* Check for special command "property default" */
-    if ((objc == 2) && (!strcmp(Tcl_GetString(objv[1]), "default"))) {
+    if ((objc == 2) && (index == TOP_DEFAULT_IDX)) {
 
 	/* For each FET device, do "merge {w add_critical}" and	*/
 	/* "remove as ad ps pd".  This allows parallel devices	*/
@@ -3531,7 +3557,7 @@ _netcmp_property(ClientData clientData,
 	}
 	return TCL_OK;
     }
-    else if ((objc == 3) && (!strcmp(Tcl_GetString(objv[1]), "parallel"))) {
+    else if ((objc == 3) && (index == TOP_PARALLEL_IDX)) {
 	if (!strcmp(Tcl_GetString(objv[2]), "none")) {
 	    GlobalParallelNone = TRUE;
 	    SetParallelCombine(FALSE);
@@ -3553,8 +3579,7 @@ _netcmp_property(ClientData clientData,
 	}
 	return TCL_OK;
     }
-    else if ((objc == 3) && ((!strcmp(Tcl_GetString(objv[1]), "series")) ||
-		(!strcmp(Tcl_GetString(objv[1]), "serial")))) {
+    else if ((objc == 3) && ((index == TOP_SERIES_IDX) || (index == TOP_SERIAL_IDX))) {
 	if (!strcmp(Tcl_GetString(objv[2]), "none")) {
 	    SetSeriesCombine(FALSE);
 	}
@@ -3568,7 +3593,7 @@ _netcmp_property(ClientData clientData,
 	}
 	return TCL_OK;
     }
-    else if ((objc > 1) && (!strcmp(Tcl_GetString(objv[1]), "topology"))) {
+    else if ((objc > 1) && (index == TOP_TOPOLOGY_IDX)) {
 	if (objc == 2) {
 	    if (ExactTopology)
 		Tcl_SetResult(interp, "Strict topology property matching.",
@@ -4014,6 +4039,32 @@ _netcmp_property(ClientData clientData,
 		}
 		break;
 
+	    case DERIVE_IDX:
+		/* Create a derived property.  For now, this just creates
+		 * "area" or "perimeter" properties.  There may not (?)
+		 * be enough cause to make other ones.  Unlike other
+		 * "property" options, this option causes the whole circuit
+		 * database to be searched for the device in question, and
+		 * the new property is added.
+		 */
+		if (objc < 6) {
+		    Tcl_WrongNumArgs(interp, 2, objv, "{area|perimeter width length}");
+		    return TCL_ERROR;
+		}
+		result = Tcl_GetIndexFromObj(interp, objv[3],
+			(CONST84 char **)deriveoptions,
+			"area|perimeter", 0, &idx2);
+		if (result != TCL_OK) return result;
+		switch (idx2) {
+		    case AREA_IDX:
+			DeriveAreaProperty(tp, fnum, Tcl_GetString(objv[4]),
+				Tcl_GetString(objv[5]));
+			break;
+		    case PERIMETER_IDX:
+			DerivePerimeterProperty(tp, fnum, Tcl_GetString(objv[4]),
+				Tcl_GetString(objv[5]));
+			break;
+		}
 	}
     }
     return TCL_OK;