diff --git a/core/views/survex.py b/core/views/survex.py
index 21d558e..935ecd9 100644
--- a/core/views/survex.py
+++ b/core/views/survex.py
@@ -271,17 +271,22 @@ def svx(request, survex_file):
             outputtype = rform.cleaned_data["outputtype"] # used by CodeMirror ajax I think
             difflist = form.DiffCode(rcode)
             # print(">>>> ", rform.data)
+            svxfile = form.survexfile
 
             if "revert" in rform.data:
                 pass
+
             if "process" in rform.data:
-                if not difflist:
+                if difflist:
+                    message = "SAVE FILE FIRST"
+                    form.data["code"] = rcode
+                elif svxfile:
                     logmessage = form.Process()
                     if logmessage:
                         message = f"OUTPUT FROM PROCESSING\n{logmessage}"
                 else:
-                    message = "SAVE FILE FIRST"
-                    form.data["code"] = rcode
+                    message = "SAVE VALID FILE FIRST"
+                    form.data["code"] = rcode                   
             if "save" in rform.data:
                 if request.user.is_authenticated:
                     message = form.SaveCode(rcode)
@@ -293,7 +298,7 @@ def svx(request, survex_file):
                 print("Differences: ")
                 form.data["code"] = rcode
 
-    # process(survex_file)
+    # GET or after POST-specific handling
     svxfile = form.survexfile # only valid once form.GetDiscCode() called
 
     if "code" not in form.data: