Index: /trunk/ippconfig/recipes/ppSub.config
===================================================================
--- /trunk/ippconfig/recipes/ppSub.config	(revision 29940)
+++ /trunk/ippconfig/recipes/ppSub.config	(revision 29941)
@@ -117,4 +117,13 @@
 END
 
+# Difference of warp - stack
+WARPSTACK_FORCED     METADATA
+	DUAL		BOOL	FALSE	# Dual convolution?
+	INVERSE		BOOL	FALSE   # Generate inverse subtraction?
+	PHOTOMETRY	BOOL	TRUE	# Perform photometry?
+	CONVOLVE.TARGET STR     SINGLE2	# convolution direction
+ FORCED.PHOTOMETRY.BOTH BOOL    TRUE    # forced photometry on input sources
+END
+
 #PR image class
 PR		METADATA
Index: /trunk/ippconfig/recipes/reductionClasses.mdc
===================================================================
--- /trunk/ippconfig/recipes/reductionClasses.mdc	(revision 29940)
+++ /trunk/ippconfig/recipes/reductionClasses.mdc	(revision 29941)
@@ -173,4 +173,12 @@
 WARPSTACK	METADATA
 	DIFF_PPSUB	STR	WARPSTACK
+	DIFF_PSPHOT	STR	DIFF
+	JPEG_BIN1	STR	PPIMAGE_J1
+	JPEG_BIN2	STR	PPIMAGE_J2
+END
+
+# reduction class specifically for warpstack diffs:
+WARPSTACK_FORCED	METADATA
+	DIFF_PPSUB	STR	WARPSTACK_FORCED
 	DIFF_PSPHOT	STR	DIFF
 	JPEG_BIN1	STR	PPIMAGE_J1