diff --git a/automaton.c b/automaton.c
index 98499e0..8997ba6 100644
--- a/automaton.c
+++ b/automaton.c
@@ -1,56 +1,41 @@
 #include <gtk-4.0/gtk/gtk.h>
 #include <assert.h>
 #include "callback.h"
+#include "automaton.h"
 
 
 /******************************************************************************/
 /*                              S T A T E S                                   */
 /******************************************************************************/
 
-// (exec / edit) X (state / rules / measure) X (observ / interpret / read / write)
+/*               (exec / edit)
+ *                     X
+ *          (state / rules / data)
+ *                     X
+ *       (measure / analyse / interpret)
+ *                     X
+ *               (read / write)
+ */
 
-enum {  //  S T A T E S
-  INTER,
-  EXEC_STOP,
-  EXEC_RUN,
-  EDIT_STATE,
-  EDIT_RULE,
-  MEASURE,
-  OBSERVE,
-  ANALYSE,
-  HELP,
-  CONFIGURE
-};
+static int status = INTER; // int  get_status () {return status;}
 
-static int status = EXEC_STOP; // int  get_status () {return status;}
-
-enum {  //  T R A N S I T I O N S
-  EXEC_TO_RUN,
-  RUN_TO_EXEC,
-  EXEC_TO_INTER,
-  INTER_TO_EDIT,
-  EDIT_TO_INTER,
-  INTER_TO_EXEC,
-};
 /******************************************************************************/
 /*                          T R A N S I T I O N S                             */
 /******************************************************************************/
 
 void SWITCH_TO (int asked) {
   switch (asked) {
-  case (0) :  //  EXEC_TO_RUN
-    status = EXEC_RUN;
+  case (INTER) :  //  BEGIN_TO_EXEC_STOP
+    status = STATE; printf ("SWITCH_TO INTER\n");
     break;
-  case (1) :  //  RUN_TO_EXEC
-    status = EXEC_STOP;
+  case (STATE) :  //  EXEC_STOP_TO_RUN
+    status = RULES; printf ("SWITCH_TO STATE\n");
     break;
-  case (2) :  //  EXEC_TO_INTER
-    status = INTER;
+  case (RULES) :  //  EXEC_RUN_TO_STOP
+    status = DATA; printf ("SWITCH_TO RULES\n");
     break;
-  case (3) :  //  EDIT_TO_INTER
-    //   Ici, il faudra prévenir l'utilisateur par une pop-up window :   TODO   (sauvegarde automatique sinon)
-    //   S'il ne prend pas la main, les données de la simulation en cours risquent d'être perdues
-    status = INTER;
+  case (DATA) :  //  EXEC_TO_INTER
+    status = INTER; printf ("SWITCH_TO DATA\n");
     break;
   default : ;
   }
@@ -67,15 +52,42 @@ void SWITCH_TO (int asked) {
 
 
 /*
+enum {  //  S T A T E S
+  INTER,
+  EXEC_STOP,
+  EXEC_RUN,
+  EDIT_STATE,
+  EDIT_RULES_TREE,
+  EDIT_RULE,
+  EDIT_MEASURE,
+  OBSERVE,
+  ANALYSE,
+  HELP,
+  CONFIGURE
+};
+
+static int status = EXEC_STOP; // int  get_status () {return status;}
+
+enum {  //  T R A N S I T I O N S
+  BEGIN_TO_EXEC_STOP
+  EXEC_STOP_TO_RUN,
+  EXEC_RUN_TO_STOP,
+  EXEC_TO_INTER,
+  INTER_TO_EDIT,
+  EDIT_TO_INTER,
+  INTER_TO_EXEC,
+};
+
+
 void set_status (int prescribed) {
   status = prescribed;   if (0) printf ("status = %d\n", status);
 
   switch (status) {
-  case (0) :  //  EXEC_STOP
+  case (0) :  //  EXEC_STOP    DATA_ANALYSIS
     status = EXEC_RUN;
     break;
   case (1) :  //  EXEC_RUN
-    //   Ici, il faudra prévenir l'utilisateur par une pop-up window :   TODO   (sauvegarde automatique sinon)
+    //   Ici, il faudra prévenir l'utilisateur par une pop-up window :     (sauvegarde automatique sinon)
     //   S'il ne prend pas la main, les données de la simulation en cours risquent d'être perdues
     status = EXEC_STOP;
     break;
diff --git a/automaton.h b/automaton.h
index b5e7e02..b6e96a9 100644
--- a/automaton.h
+++ b/automaton.h
@@ -4,3 +4,6 @@
 void set_status (int prescribed);
 int  get_status ();
 
+enum choice { INTER, STATE, RULES, DATA };
+
+void SWITCH_TO (int asked);
diff --git a/callback.c b/callback.c
index 92f2d6f..6840698 100644
--- a/callback.c
+++ b/callback.c
@@ -199,11 +199,13 @@ void on_toggle_observ_interpret (GtkWidget *btt_toggle_observ_interpret, gpointe
 void on_SAVE_CURRENT_MODEL_BEFORE_EDITING (GtkWidget *btt_SAVE_CURRENT_MODEL, gpointer data) {
   gtk_widget_set_sensitive (GTK_WIDGET (data), TRUE);
   printf ("callback.c (line 201)  -  SAVE_CURRENT_MODEL_BEFORE_EDITING\n");
+  SWITCH_TO (INTER);
 }
 
 void on_DISCARD_CURRENT_MODEL_AND_START_EDITING (GtkWidget *btt_SAVE_CURRENT_MODEL, gpointer data) {
   gtk_window_close (GTK_WINDOW (data));
   printf ("callback.c (line 206)  -  DISCARD_CURRENT_MODEL_AND_START_EDITING\n");
+  SWITCH_TO (RULES);
 }
 
 void on_WRITE_CURRENT_MODEL (GtkWidget *btt_WRITE_CURRENT_MODEL, gpointer data) {