Index: trunk/ippTools/src/difftool.c
===================================================================
--- trunk/ippTools/src/difftool.c	(revision 23737)
+++ trunk/ippTools/src/difftool.c	(revision 23740)
@@ -1275,10 +1275,17 @@
     PXOPT_COPY_STR(config->args, selectWhere, "-input_label", "inputWarpRun.label", "==");
     PXOPT_COPY_STR(config->args, selectWhere, "-template_label", "templateWarpRun.label", "==");
+    PXOPT_COPY_F32(config->args, selectWhere, "-rotdiff", "ABS(inputRawExp.posang - templateRawExp.posang)", "<=");
     PXOPT_COPY_F32(config->args, selectWhere, "-timediff",
                    "ABS(TIME_TO_SEC(TIMEDIFF(inputRawExp.dateobs, templateRawExp.dateobs)))", "<=");
-    PXOPT_COPY_F32(config->args, selectWhere, "-rotdiff", "ABS(inputRawExp.posang - templateRawExp.posang)", "<=");
+
     // Haversine formula for great circle distance
     PXOPT_COPY_F32(config->args, selectWhere, "-distance",
                    "DEGREES(2*ASIN(SQRT(POW(SIN(inputRawExp.decl - templateRawExp.decl),2) + COS(inputRawExp.decl)*COS(templateRawExp.decl)*POW(SIN(inputRawExp.ra - templateRawExp.ra),2))))", "<=");
+
+    PXOPT_LOOKUP_BOOL(backwards, config->args, "-backwards", false);
+
+    psMetadataAddF32(selectWhere, PS_LIST_TAIL,
+                     "TIME_TO_SEC(TIMEDIFF(inputRawExp.dateobs, templateRawExp.dateobs))",
+                     PS_META_DUPLICATE_OK, backwards ? "<" : ">", 0.0);
 
     // Restrictions for inserting skycells
Index: trunk/ippTools/src/difftoolConfig.c
===================================================================
--- trunk/ippTools/src/difftoolConfig.c	(revision 23737)
+++ trunk/ippTools/src/difftoolConfig.c	(revision 23740)
@@ -174,4 +174,5 @@
     psMetadataAddStr(definewarpwarpArgs, PS_LIST_TAIL, "-obs_mode", 0, "search by observation mode", NULL);
     psMetadataAddF32(definewarpwarpArgs, PS_LIST_TAIL, "-timediff", 0, "limit time difference between input and template", NAN);
+    psMetadataAddBool(definewarpwarpArgs, PS_LIST_TAIL, "-backwards", 0, "Template comes after input?", false);
     psMetadataAddF32(definewarpwarpArgs, PS_LIST_TAIL, "-rotdiff", 0, "limit rotator difference between input and template", NAN);
     psMetadataAddStr(definewarpwarpArgs, PS_LIST_TAIL, "-input_label", 0, "search by warp label for input", NULL);