Index: trunk/ppMerge/src/ppMergeOptions.c
===================================================================
--- trunk/ppMerge/src/ppMergeOptions.c	(revision 7073)
+++ trunk/ppMerge/src/ppMergeOptions.c	(revision 7260)
@@ -137,5 +137,5 @@
     OPTION_PARSE(options->combine->fracLow,  recipe, "FRACLOW",   F32 );
     OPTION_PARSE(options->combine->nKeep,    recipe, "NKEEP",     S32 );
-    OPTION_PARSE(options->combine->maskVal,  recipe, "MASKVAL",   U8  );
+    OPTION_PARSE(options->combine->maskVal,  recipe, "MASKVAL",   S32 );
     options->combine->combine = parseStat(recipe, "COMBINE");
     options->background       = parseStat(recipe, "BACKGROUND");
@@ -145,28 +145,41 @@
     // Set options based on the type of calibration frame
     const char *type = psMetadataLookupStr(NULL, config->arguments, "-type"); // The type of calibration frame
-    if (strcasecmp(type, "BIAS") == 0) {
+    if (strlen(type) > 0) {
+        if (strcasecmp(type, "BIAS") == 0) {
+            options->zero = false;
+            options->scale = false;
+            options->exptime = false;
+        } else if (strcasecmp(type, "DARK") == 0) {
+            options->zero = false;
+            options->scale = false;
+            options->exptime = true;
+        } else if (strcasecmp(type, "FLAT") == 0) {
+            options->zero = false;
+            options->scale = true;
+            options->exptime = false;
+        } else if (strcasecmp(type, "FRINGE") == 0) {
+            options->zero = true;
+            options->scale = true;
+            options->exptime = false;
+        } else {
+            psLogMsg(__func__, PS_LOG_WARN, "Unrecognised image type: %s --- assuming BIAS.\n", type);
+            options->zero = false;
+            options->scale = false;
+            options->exptime = false;
+        }
+    } else {
+        psLogMsg(__func__, PS_LOG_WARN, "No calibration type specified; assuming BIAS.\n");
         options->zero = false;
         options->scale = false;
         options->exptime = false;
-    } else if (strcasecmp(type, "DARK") == 0) {
-        options->zero = false;
-        options->scale = false;
-        options->exptime = true;
-    } else if (strcasecmp(type, "FLAT") == 0) {
-        options->zero = false;
-        options->scale = true;
-        options->exptime = false;
-    } else if (strcasecmp(type, "FRINGE") == 0) {
-        options->zero = true;
-        options->scale = true;
-        options->exptime = false;
-    } else {
-        psLogMsg(__func__, PS_LOG_WARN, "Unrecognised image type: %s --- ignored.\n", type);
     }
 
+
+#if 0
     // Or you can set them individually
     OPTION_PARSE(options->zero,    config->arguments, "-zero",    Bool);
     OPTION_PARSE(options->scale,   config->arguments, "-scale",   Bool);
     OPTION_PARSE(options->exptime, config->arguments, "-exptime", Bool);
+#endif
 
     // Number of on/off images