diff --git a/VERSION b/VERSION
index 119b32c6..6951ac29 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-8.3.626
+8.3.627
diff --git a/drc/DRCbasic.c b/drc/DRCbasic.c
index b2692fe6..ef5b7df9 100644
--- a/drc/DRCbasic.c
+++ b/drc/DRCbasic.c
@@ -765,13 +765,12 @@ drcTile (tile, dinfo, arg)
 			cptr = cptr->drcc_next)
 	    {
 		/* Handle rule exceptions and exemptions */
-		if (cptr->drcc_exception != (char)DRC_EXCEPTION_NONE)
+		if (cptr->drcc_exception != DRC_EXCEPTION_NONE)
 		{
 		    PropertyRecord *proprec;
 		    bool propfound, isinside = FALSE;
 		    char *name;
-		    signed char idx = cptr->drcc_exception;
-		    if (idx < 0) idx = -idx - 1;
+		    int idx = cptr->drcc_exception & ~DRC_EXCEPTION_MASK;
 		    name = DRCCurStyle->DRCExceptionList[idx];
 
 		    /* Is there any exception area defined? */
@@ -797,8 +796,10 @@ drcTile (tile, dinfo, arg)
 		     * an exception area.  Exception rules are ignored if
 		     * the edge is outside an exception area.
 		     */
-		    if (!isinside && (cptr->drcc_exception >= 0)) continue;
-		    if (isinside && (cptr->drcc_exception < 0)) continue;
+		    if (!isinside && ((cptr->drcc_exception & DRC_EXCEPTION_MASK) == 0)))
+			continue;
+		    if (isinside && ((cptr->drcc_exception & DRC_EXCEPTION_MASK) == 1)))
+			continue;
 		}
 
 	    	/* DRC_ANGLES_90 and DRC_SPLITTILE rules are handled by	*/
@@ -1211,24 +1212,17 @@ drcTile (tile, dinfo, arg)
 				cptr = cptr->drcc_next)
 	    {
 		/* Handle rule exceptions and exemptions */
-		if (cptr->drcc_exception != (char)DRC_EXCEPTION_NONE)
+		if (cptr->drcc_exception != DRC_EXCEPTION_NONE)
 		{
 		    PropertyRecord *proprec;
 		    bool propfound, isinside = FALSE;
 		    char *name;
-		    signed char idx = cptr->drcc_exception;
-		    if (idx < 0) idx = -idx - 1;
+		    int idx = cptr->drcc_exception & ~DRC_EXCEPTION_MASK;
 		    name = DRCCurStyle->DRCExceptionList[idx];
 
 		    /* Is there any exception area defined? */
 		    proprec = DBPropGet(arg->dCD_celldef, name, &propfound);
 
-		    /* Quickest case:  Rule is an exception but there are no
-		     * exception areas.
-		     */
-		    if ((!propfound) && (cptr->drcc_exception >= 0))
-			continue;
-
 		    /* If an exception area exists, is the error edge inside? */
 		    if (propfound)
 		    {
@@ -1249,8 +1243,10 @@ drcTile (tile, dinfo, arg)
 		     * an exception area.  Exception rules are ignored if
 		     * the edge is outside an exception area.
 		     */
-		    if (isinside && (cptr->drcc_exception < 0)) continue;
-		    if (!isinside && (cptr->drcc_exception >= 0)) continue;
+		    if (!isinside && ((cptr->drcc_exception & DRC_EXCEPTION_MASK) == 0)))
+			continue;
+		    if (isinside && ((cptr->drcc_exception & DRC_EXCEPTION_MASK) == 1)))
+			continue;
 		}
 
 	    	/* DRC_ANGLES_90 and DRC_SPLITTILE rules are handled by	*/
diff --git a/drc/DRCtech.c b/drc/DRCtech.c
index c15e9f96..e2193ad8 100644
--- a/drc/DRCtech.c
+++ b/drc/DRCtech.c
@@ -76,7 +76,7 @@ static int DRCtag = 0;
  * while reading the DRC tech file section.
  */
 
-static signed char drcCurException = (char)DRC_EXCEPTION_NONE;
+static unsigned char drcCurException = DRC_EXCEPTION_NONE;
 
 /*
  * Forward declarations.
@@ -405,7 +405,9 @@ drcWhyCreate(whystring)
  * not already exist.
  *
  * Results:
- *	The index of the exception (which is a signed character).
+ *	The index of the exception (which is an unsigned character containing
+ *	the index in the lower 7 bits and a high bit indicating if the rule
+ *	is an exception (0) or an exemption (1)).
  *
  * Side effects:
  *	Adds to the DRCExceptionList if "name" has not been used before.
@@ -414,7 +416,7 @@ drcWhyCreate(whystring)
  * ----------------------------------------------------------------------------
  */
 
-char
+unsigned char
 drcExceptionCreate(name)
     char *name;
 {
@@ -424,13 +426,14 @@ drcExceptionCreate(name)
     /* NOTE:  DRCExceptionList has "MASKHINTS_" prepended to the names */
     for (i = 0; i < DRCCurStyle->DRCExceptionSize; i++)
 	if (!strcmp(name, DRCCurStyle->DRCExceptionList[i] + 10))
-	    return (char)i;
+	    return (unsigned char)i;
 
-    if (i > 127)
+    /* Note that i cannot be 127 as this is reserved for DRC_EXCEPTION_NONE */
+    if (i > 126)
     {
 	/* I would be shocked if this code ever got executed. */
-	TxError("Error:  Too many rule exceptions!  Limit is 127.\n");
-	return (char)DRC_EXCEPTION_NONE;
+	TxError("Error:  Too many rule exceptions!  Limit is 126.\n");
+	return DRC_EXCEPTION_NONE;
     }
 
     /* Create a new list that is one entry longer than the old list.
@@ -448,7 +451,7 @@ drcExceptionCreate(name)
     if (DRCCurStyle->DRCExceptionList != (char **)NULL)
 	freeMagic(DRCCurStyle->DRCExceptionList);
     DRCCurStyle->DRCExceptionList = newlist;
-    return (char)i;
+    return (unsigned char)i;
 }
     
 /*
@@ -732,7 +735,7 @@ DRCTechStyleInit()
 	    }
 
     drcCifInit();
-    drcCurException = (char)DRC_EXCEPTION_NONE;
+    drcCurException = DRC_EXCEPTION_NONE;
 }
 
 /*
@@ -3726,9 +3729,10 @@ drcRectangle(argc, argv)
  *	Returns 0.
  *
  * Side effects:
- *	Updates drcCurException.  drcCurException is zero or positive for 
- *	exceptions and negative for exemptions.  The index can be
- *	recovered from a negative value by negating it and subtracting 1.
+ *	Updates drcCurException.  drcCurException contains the index in
+ *	the lower 7 bits, and a flag in the upper bit (0 = exception rule,
+ *	1 = exemption rule).  The index can be recovered by masking off
+ *	the upper bit.
  *
  * ----------------------------------------------------------------------------
  */
@@ -3745,7 +3749,7 @@ drcException(argc, argv)
     /* Assume that argc must be 2 because the parser insists upon it */
 
     if (!strcmp(argv[1], "none"))
-	drcCurException = (char)DRC_EXCEPTION_NONE;
+	drcCurException = DRC_EXCEPTION_NONE;
     else
 	drcCurException = drcExceptionCreate(argv[1]);
     return (0);
@@ -3763,9 +3767,9 @@ drcExemption(argc, argv)
     /* Assume that argc must be 2 because the parser insists upon it */
 
     if (!strcmp(argv[1], "none"))
-	drcCurException = (char)DRC_EXCEPTION_NONE;
+	drcCurException = DRC_EXCEPTION_NONE;
     else
-	drcCurException = -(drcExceptionCreate(argv[1])) - 1;
+	drcCurException = drcExceptionCreate(argv[1]) | DRC_EXCEPTION_MASK;
     return (0);
 }
 
diff --git a/drc/drc.h b/drc/drc.h
index 82ed32af..fbd1b96b 100644
--- a/drc/drc.h
+++ b/drc/drc.h
@@ -36,7 +36,7 @@ typedef struct drccookie
     TileTypeBitMask   drcc_mask;	/* Legal types on RHS */
     TileTypeBitMask   drcc_corner;	/* Types that trigger corner check */
     unsigned short    drcc_flags;	/* Miscellaneous flags, see below. */
-    signed char       drcc_exception;	/* Index to list of exceptions */
+    unsigned char     drcc_exception;	/* Index to list of exceptions */
     int		      drcc_edgeplane;	/* Plane of edge */
     int		      drcc_plane;	/* Index of plane on which to check
 					 * legal types. */
@@ -92,8 +92,10 @@ typedef struct drccookie
 #define DRC_UNPROCESSED 		CLIENTDEFAULT
 #define DRC_PROCESSED 			1
 
-/* drcc_exception defaults to -128 (0x80) meaning no exceptions/exemptions */
-#define	DRC_EXCEPTION_NONE (char)0x80
+/* drcc_exception defaults to 255 meaning no exceptions/exemptions */
+#define	DRC_EXCEPTION_NONE ((unsigned char)0xff)
+/* The high bit of the value determines if this is an exception or an exemption.
+#define DRC_EXCEPTION_MASK ((unsigned char)0x80)
 
 /*
  * Background DRC (DRC Idle proc) for Tcl-based Magic