Index: trunk/ppMerge/src/ppMergeScaleZero.c
===================================================================
--- trunk/ppMerge/src/ppMergeScaleZero.c	(revision 9325)
+++ trunk/ppMerge/src/ppMergeScaleZero.c	(revision 9463)
@@ -47,5 +47,5 @@
     assert(config);
 
-    if (!options->scale && !options->zero && !options->exptime) {
+    if (!options->scale && !options->zero && !options->darktime) {
         return true;                    // We did everything we were asked for
     }
@@ -161,11 +161,11 @@
     psStats *bgStats = psStatsAlloc(options->mean); // Statistic to measure the background
     psVector *gains = NULL;             // The gains for each cell
-    psImage *exptime = NULL;            // The exposure time for each integration of each cell
+    psImage *darktime = NULL;           // The dark time for each integration of each cell
     if (options->scale) {
         gains = psVectorAlloc(data->numCells, PS_TYPE_F32);
         gains->n = data->numCells;
     }
-    if (options->exptime) {
-        exptime = psImageAlloc(data->numCells, filenames->n, PS_TYPE_F32);
+    if (options->darktime) {
+        darktime = psImageAlloc(data->numCells, filenames->n, PS_TYPE_F32);
     }
 
@@ -199,11 +199,11 @@
 
                 // Normalising by the exposure time
-                if (options->exptime) {
-                    exptime->data.F32[i][cellNum] = psMetadataLookupF32(&mdok, cell->concepts,
-                                                                        "CELL.EXPOSURE");
-                    if (!mdok || isnan(exptime->data.F32[i][cellNum])) {
-                        psLogMsg(__func__, PS_LOG_WARN, "CELL.EXPOSURE for file %s chip %d cell %d is not "
+                if (options->darktime) {
+                    darktime->data.F32[i][cellNum] = psMetadataLookupF32(&mdok, cell->concepts,
+                                                                        "CELL.DARKTIME");
+                    if (!mdok || isnan(darktime->data.F32[i][cellNum])) {
+                        psLogMsg(__func__, PS_LOG_WARN, "CELL.DARKTIME for file %s chip %d cell %d is not "
                                  "set.\n", name, j, k);
-                        exptime->data.F32[i][cellNum] = NAN;
+                        darktime->data.F32[i][cellNum] = NAN;
                         status = false;
                     }
@@ -302,10 +302,10 @@
     }
 
-    if (options->exptime) {
+    if (options->darktime) {
         if (!options->scale) {
             // Copy over the exposure times
-            *scales = psImageCopy(*scales, exptime, PS_TYPE_F32);
+            *scales = psImageCopy(*scales, darktime, PS_TYPE_F32);
         } else {
-            *scales = (psImage*)psBinaryOp(*scales, *scales, "*", exptime);
+            *scales = (psImage*)psBinaryOp(*scales, *scales, "*", darktime);
         }
     }