Index: trunk/ppMops/src/ppMops.c
===================================================================
--- trunk/ppMops/src/ppMops.c	(revision 25076)
+++ trunk/ppMops/src/ppMops.c	(revision 25100)
@@ -6,7 +6,7 @@
 int main(int argc, char *argv[])
 {
-    if (argc != 6) {
+    if (argc != 7) {
         fprintf(stderr, "Insufficient arguments.\n");
-        fprintf(stderr, "Usage: %s DETECTIONS ZP EXP_ID EXP_NAME OUTPUT\n", argv[0]);
+        fprintf(stderr, "Usage: %s DETECTIONS ZP EXP_ID EXP_NAME DIRECTION OUTPUT\n", argv[0]);
         exit(PS_EXIT_CONFIG_ERROR);
     }
@@ -17,5 +17,6 @@
     data->exp_id = atoll(argv[3]);
     data->exp_name = psStringCopy(argv[4]);
-    data->output = psStringCopy(argv[5]);
+    data->direction = atoi(argv[5]);
+    data->output = psStringCopy(argv[6]);
 
     if (!isfinite(data->zp)) {
@@ -128,5 +129,4 @@
                                         psMetadataLookupF32(NULL, header, "FWHM_MIN"));
 
-
         psMetadataAddStr(outHeader, PS_LIST_TAIL, "RA", 0, "Right ascension of boresight", ra);
         psMetadataAddStr(outHeader, PS_LIST_TAIL, "DEC", 0, "Declination of boresight", dec);
@@ -141,9 +141,10 @@
         psMetadataAddStr(outHeader, PS_LIST_TAIL, "FPA_ID", 0, "Exposure name", data->exp_name);
         psMetadataAddS64(outHeader, PS_LIST_TAIL, "EXP_ID", 0, "Exposure identifier", data->exp_id);
+        psMetadataAddBool(outHeader, PS_LIST_TAIL, "POSITIVE", 0, "Positive subtraction?", data->direction);
         psMetadataAddStr(outHeader, PS_LIST_TAIL, "OBSCODE", 0, "IAU Observatory code", OBSERVATORY_CODE);
         psMetadataAddF32(outHeader, PS_LIST_TAIL, "STARPSF", 0, "Stellar PSF (arcsec)", psf);
 
         // These are completely fake
-        psMetadataAddF32(outHeader, PS_LIST_TAIL, "LIMITMAG", 0, "Limiting magnitude (FAKE)", 25.0);
+        psMetadataAddF32(outHeader, PS_LIST_TAIL, "LIMITMAG", 0, "Limiting magnitude (FAKE)", 99.0);
         psMetadataAddF32(outHeader, PS_LIST_TAIL, "DE1", 0, "Detection efficiency (FAKE)", 0.0);
         psMetadataAddF32(outHeader, PS_LIST_TAIL, "DE2", 0, "Detection efficiency (FAKE)", 0.0);
Index: trunk/ppMops/src/ppMops.h
===================================================================
--- trunk/ppMops/src/ppMops.h	(revision 25076)
+++ trunk/ppMops/src/ppMops.h	(revision 25100)
@@ -18,4 +18,5 @@
     psS64 exp_id;                       // Exposure identifier
     psString exp_name;                  // Exposure name
+    bool direction;                     // Direction of subtraction, 1=positive, 0=negative
     psString output;                    // Output filename
 } ppMopsData;