Index: trunk/ppStack/src/ppStackArguments.c
===================================================================
--- trunk/ppStack/src/ppStackArguments.c	(revision 21366)
+++ trunk/ppStack/src/ppStackArguments.c	(revision 21477)
@@ -147,4 +147,6 @@
     psMetadataAddF32(arguments, PS_LIST_TAIL, "-combine-sys", 0,
                      "Relative systematic error in combination", NAN);
+    psMetadataAddF32(arguments, PS_LIST_TAIL, "-combine-discard", 0,
+                     "Discard fraction for Olympic weighted mean", NAN);
     psMetadataAddStr(arguments, PS_LIST_TAIL, "-mask-val", 0, "Mask value of input bad pixels", NULL);
     psMetadataAddStr(arguments, PS_LIST_TAIL, "-mask-bad", 0, "Mask value to give bad pixels", NULL);
@@ -232,12 +234,13 @@
     }
 
-    VALUE_ARG_RECIPE_INT("-iter",             "ITER",           S32, 0);
-    VALUE_ARG_RECIPE_FLOAT("-combine-rej",    "COMBINE.REJ",    F32);
-    VALUE_ARG_RECIPE_FLOAT("-combine-sys",    "COMBINE.SYS",    F32);
-    VALUE_ARG_RECIPE_FLOAT("-threshold-mask", "THRESHOLD.MASK", F32);
-    VALUE_ARG_RECIPE_FLOAT("-image-rej",      "IMAGE.REJ",      F32);
-    VALUE_ARG_RECIPE_FLOAT("-deconv-limit",   "DECONV.LIMIT",   F32);
-    VALUE_ARG_RECIPE_INT("-rows",             "ROWS",           S32, 0);
-    VALUE_ARG_RECIPE_FLOAT("-poor-frac",      "POOR.FRACTION",  F32);
+    VALUE_ARG_RECIPE_INT("-iter",              "ITER",            S32, 0);
+    VALUE_ARG_RECIPE_FLOAT("-combine-rej",     "COMBINE.REJ",     F32);
+    VALUE_ARG_RECIPE_FLOAT("-combine-sys",     "COMBINE.SYS",     F32);
+    VALUE_ARG_RECIPE_FLOAT("-combine-discard", "COMBINE.DISCARD", F32);
+    VALUE_ARG_RECIPE_FLOAT("-threshold-mask",  "THRESHOLD.MASK",  F32);
+    VALUE_ARG_RECIPE_FLOAT("-image-rej",       "IMAGE.REJ",       F32);
+    VALUE_ARG_RECIPE_FLOAT("-deconv-limit",    "DECONV.LIMIT",    F32);
+    VALUE_ARG_RECIPE_INT("-rows",              "ROWS",            S32, 0);
+    VALUE_ARG_RECIPE_FLOAT("-poor-frac",       "POOR.FRACTION",   F32);
 
     valueArgRecipeStr(arguments, recipe, "-mask-val",  "MASK.VAL",  recipe);