Index: trunk/ppTranslate/src/ppMops.c
===================================================================
--- trunk/ppTranslate/src/ppMops.c	(revision 28623)
+++ trunk/ppTranslate/src/ppMops.c	(revision 29565)
@@ -3,4 +3,35 @@
 
 #include "ppMops.h"
+
+/*
+  Behavior:
+
+  If the CMF input files have different versions, merging cannot be
+  performed.
+
+  If -version option is not given: 
+    the output version is the version of the input file(s)
+  otherwise
+    the output version is (possibly forced to) the version option
+
+  If the input file(s) version is equals to the version option:
+    no change in version (neither data creation nor data loss)
+  If the input file(s) version is strictly less than the version option:
+    Data for version option are set tp default values: 0, NaN, NULL
+  If the input file(s) version is strictly greater than the version option:
+    Data are those of the lower version
+
+  Example:
+   -> ppMops dv1_input_files_list output -version 1
+      is the same as 'ppMops dv1_input_files_list output'
+   -> ppMops dv1_input_files_list output -version 1
+      is the same as 'ppMops dv1_input_files_list output'
+   -> ppMops dv1_input_files_list output -version 2
+      Aggregate DV1 values and add default DV2 values
+      Saved as DV2 file
+   -> ppMops dv2_input_files_list output -version 1
+      Aggregate DV1 values and truncate DV2 values 
+      Saved as DV1 file
+ */
 
 int main(int argc, char *argv[])