Index: trunk/ppImage/src/ppImageArguments.c
===================================================================
--- trunk/ppImage/src/ppImageArguments.c	(revision 9958)
+++ trunk/ppImage/src/ppImageArguments.c	(revision 10209)
@@ -6,14 +6,30 @@
 
 static void usage (void) {
-    fprintf (stderr, "USAGE: ppImage [-file INPUT.fits] [-list INPUT.txt] OUTPUT\n");
+    fprintf(stderr, "USAGE: ppImage [-file INPUT.fits] [-list INPUT.txt] OUTPUT\n\n");
+    fprintf(stderr, "Optional arguments:\n");
+    fprintf(stderr, "\t-stat STAT.mdc: Output statistics into STAT.mdc\n");
+    fprintf(stderr, "\t-isfringe: The input image contains fringe data.\n");
+    fprintf(stderr, "\t-usemask MASKVAL: Use this mask value (override recipe).\n");
+    fprintf(stderr, "\t-chip CHIPNUM: Only process this chip number.\n");
+    fprintf(stderr, "\t-norm VALUE: Divide through by this value when done.\n");
+    fprintf(stderr, "\n");
+    fprintf(stderr, "Input options (single file / file list):\n");
+    fprintf(stderr, "\t-bias/-biaslist: Bias image.\n");
+    fprintf(stderr, "\t-dark/-darklist: Dark image.\n");
+    fprintf(stderr, "\t-shutter/-shutterlist: Shutter image.\n");
+    fprintf(stderr, "\t-flat/-flatlist: Flat image.\n");
+    fprintf(stderr, "\t-mask/-masklist: Mask image.\n");
+    fprintf(stderr, "\t-fringe/-fringelist: Fringe image and data.\n");
+    fprintf(stderr, "\n");
     exit (2);
 }
 
-pmConfig *ppImageArguments(int argc, char **argv) {
+pmConfig *ppImageArguments(int argc, char **argv)
+{
+    int argnum;                         // Argument number of interest
 
-    int N;
-    bool status;
-
-    if (argc == 1) usage ();
+    if (argc == 1) {
+        usage();
+    }
 
     // load the site-wide configuration information
@@ -28,13 +44,13 @@
     psMetadataAddPtr (config->arguments, PS_LIST_TAIL, "PPIMAGE.OPTIONS",  PS_DATA_METADATA, "", options);
 
-    if ((N = psArgumentGet(argc, argv, "-stat"))) {
-        psArgumentRemove(N, &argc, argv);
+    if ((argnum = psArgumentGet(argc, argv, "-stat"))) {
+        psArgumentRemove(argnum, &argc, argv);
         psMetadataAddStr(options, PS_LIST_TAIL, "STATS", PS_META_REPLACE,
-                         "Filename for summary statistics", argv[N]);
-        psArgumentRemove(N, &argc, argv);
+                         "Filename for summary statistics", argv[argnum]);
+        psArgumentRemove(argnum, &argc, argv);
     }
 
-    if ((N = psArgumentGet(argc, argv, "-isfringe"))) {
-        psArgumentRemove(N, &argc, argv);
+    if ((argnum = psArgumentGet(argc, argv, "-isfringe"))) {
+        psArgumentRemove(argnum, &argc, argv);
         psMetadataAddBool(options, PS_LIST_TAIL, "INPUT_IS_FRINGE", PS_META_REPLACE,
                           "Input is fringe image", true);
@@ -44,8 +60,8 @@
 
     // recipe option: -usemask : override MASK setting in phase2.recipe
-    if ((N = psArgumentGet(argc, argv, "-usemask"))) {
-        psArgumentRemove (N, &argc, argv);
+    if ((argnum = psArgumentGet(argc, argv, "-usemask"))) {
+        psArgumentRemove (argnum, &argc, argv);
         psMetadataAddBool (options, PS_LIST_TAIL, "MASK", PS_META_REPLACE, "", true);
-        psArgumentRemove (N, &argc, argv);
+        psArgumentRemove (argnum, &argc, argv);
     }
 
@@ -56,6 +72,8 @@
 
     // the input file is a required argument; if not found, we will exit
-    status = pmConfigFileSetsMD (config->arguments, config, "INPUT", "-file", "-list");
-    if (!status) { usage ();}
+    bool status = pmConfigFileSetsMD (config->arguments, config, "INPUT", "-file", "-list");
+    if (!status) {
+        usage ();
+    }
 
     // if these command-line options are supplied, load the file name lists into config->arguments
@@ -69,18 +87,18 @@
 
     // chip selection is used to limit chips to be processed
-    if ((N = psArgumentGet (argc, argv, "-chip"))) {
-        psArgumentRemove (N, &argc, argv);
+    if ((argnum = psArgumentGet (argc, argv, "-chip"))) {
+        psArgumentRemove (argnum, &argc, argv);
         psMetadataAddStr (config->arguments, PS_LIST_TAIL, "CHIP_SELECTIONS", PS_DATA_STRING, "",
-                          argv[N]);
-        psArgumentRemove (N, &argc, argv);
+                          argv[argnum]);
+        psArgumentRemove (argnum, &argc, argv);
     }
 
     // Optional normalisation factor
-    if ((N = psArgumentGet(argc, argv, "-norm"))) {
-        psArgumentRemove(N, &argc, argv);
-        float norm = atof(argv[N]);
+    if ((argnum = psArgumentGet(argc, argv, "-norm"))) {
+        psArgumentRemove(argnum, &argc, argv);
+        float norm = atof(argv[argnum]);
         psMetadataAddF32(config->arguments, PS_LIST_TAIL, "NORMALISATION", 0,
                          "Normalisation to apply", norm);
-        psArgumentRemove(N, &argc, argv);
+        psArgumentRemove(argnum, &argc, argv);
     }
 
@@ -88,6 +106,5 @@
 
     // Add the input and output images (which remain on the command-line) to the arguments list
-    psMetadataAddStr(config->arguments, PS_LIST_TAIL, "OUTPUT", 0, "Name of the output image",
-                     argv[1]);
+    psMetadataAddStr(config->arguments, PS_LIST_TAIL, "OUTPUT", 0, "Name of the output image", argv[1]);
 
     return config;