diff --git a/html/ajax.php b/html/ajax.php
index 5bf62668d..4219a4cda 100644
--- a/html/ajax.php
+++ b/html/ajax.php
@@ -56,7 +56,7 @@ if (isset($_REQUEST['plugin_code']) )
     if ( $ext->search($_REQUEST['plugin_code']) != -1)
     {
         /* security */
-        if ( !isset ($_SESSION['g_user']) || $ext->can_request($_SESSION['g_user']) == 0 )
+        if ( !isset ($_SESSION[SESSION_KEY.'g_user']) || $ext->can_request($_SESSION[SESSION_KEY.'g_user']) == 0 )
         {
             exit();
         }
diff --git a/html/do.php b/html/do.php
index 49a2dccea..9a8641286 100644
--- a/html/do.php
+++ b/html/do.php
@@ -42,7 +42,7 @@ if ( ! isset($_REQUEST['gDossier']))
     redirect('user_login.php');
     exit();
 }
-if ( ! isset ($_SESSION['g_theme']))
+if ( ! isset ($_SESSION[SESSION_KEY.'g_theme']))
   {
     echo "<h2>"._('Vous  êtes déconnecté')."</h2>";
     $backurl=$_SERVER['REQUEST_URI'];
@@ -68,7 +68,7 @@ if ( ! $cn->exist_table('version')) {
     return;
 }
 
-$style_user=$http->post("style_user","string",$_SESSION['g_theme']);
+$style_user=$http->post("style_user","string",$_SESSION[SESSION_KEY.'g_theme']);
 
 html_page_start($style_user);
 if ( DEBUG ) {
diff --git a/html/extension.raw.php b/html/extension.raw.php
index d8f8abb72..99a5729dd 100644
--- a/html/extension.raw.php
+++ b/html/extension.raw.php
@@ -45,7 +45,7 @@ $ext=new Extension($cn);
 if ( $ext->search($http->request("plugin_code")) != -1 )
   {
     /* security */
-    if ( !isset ($_SESSION['g_user']) || $ext->can_request($_SESSION['g_user']) == 0 )
+    if ( !isset ($_SESSION[SESSION_KEY.'g_user']) || $ext->can_request($_SESSION[SESSION_KEY.'g_user']) == 0 )
       {
 		exit();
       }
diff --git a/html/fid.php b/html/fid.php
index 2b6c38964..471a08de9 100644
--- a/html/fid.php
+++ b/html/fid.php
@@ -56,7 +56,7 @@ $fTva_id=$hi->request("t","string","none");
 $fPrice_sale=$hi->request("p","string","none");
 $fPrice_purchase=$hi->request("b","string","none");
 
-if ( isset($_SESSION['isValid']) && $_SESSION['isValid'] == 1)
+if ( isset($_SESSION[SESSION_KEY.'isValid']) && $_SESSION[SESSION_KEY.'isValid'] == 1)
 {
     $jrn=$hi->get('j', "number",'-1');
     $d=$hi->get('d',"string", '');
diff --git a/html/install.php b/html/install.php
index 821df7a8c..7e4ff5d8f 100644
--- a/html/install.php
+++ b/html/install.php
@@ -145,7 +145,7 @@ load_all_script();
 echo '<div id="info_div"></div>';
 if ( $_GET['lang'] == "en_US.utf8" || $_GET['lang']=='fr_FR.utf8')
 {
-    $_SESSION['g_lang']=$_GET['lang'];
+    $_SESSION[SESSION_KEY.'g_lang']=$_GET['lang'];
     set_language();
 }
 ?>
diff --git a/html/login.php b/html/login.php
index 089040878..face7be1a 100644
--- a/html/login.php
+++ b/html/login.php
@@ -39,8 +39,8 @@ if (  isset ($_POST["p_user"] ) )
 {
     $g_user=strtolower(sql_string($_POST["p_user"]));
     $g_pass=$_POST["p_pass"];
-    $_SESSION['g_user']=$g_user;
-    $_SESSION['g_pass']=$g_pass;
+    $_SESSION[SESSION_KEY.'g_user']=$g_user;
+    $_SESSION[SESSION_KEY.'g_pass']=$g_pass;
 
 
 
diff --git a/html/popup.php b/html/popup.php
index b985af528..44bfdf57d 100644
--- a/html/popup.php
+++ b/html/popup.php
@@ -32,7 +32,7 @@ $http=new HttpInput();
 /*
  * Check if the user is still connected
  */
-if (  ! isset ($_SESSION['g_user'] ) )
+if (  ! isset ($_SESSION[SESSION_KEY.'g_user'] ) )
 {
     echo "<h2>"._('Vous  êtes déconnecté')."</h2>";
     $backurl=$_SERVER['REQUEST_URI'];
@@ -42,7 +42,7 @@ if (  ! isset ($_SESSION['g_user'] ) )
 }
 
 
-html_page_start($_SESSION['g_theme']);
+html_page_start($_SESSION[SESSION_KEY.'g_theme']);
 echo '<div style="float:left;">';
 ?>
 <script>
diff --git a/html/recherche.php b/html/recherche.php
index aa655ca6e..939256944 100644
--- a/html/recherche.php
+++ b/html/recherche.php
@@ -28,13 +28,13 @@ require_once NOALYSS_INCLUDE.'/class/acc_ledger.class.php';
 require_once NOALYSS_INCLUDE.'/class/acc_ledger_search.class.php';
 require_once NOALYSS_INCLUDE.'/lib/icon_action.class.php';
 require_once NOALYSS_INCLUDE.'/lib/http_input.class.php';
-if ( ! isset ($_SESSION['g_theme']))
+if ( ! isset ($_SESSION[SESSION_KEY.'g_theme']))
 {
     echo "<h2>"._('Vous  êtes déconnecté')."</h2>";
     die();
 }
 
-html_page_start($_SESSION['g_theme']);
+html_page_start($_SESSION[SESSION_KEY.'g_theme']);
 
 load_all_script();
 
@@ -101,7 +101,7 @@ if ( isset ($_GET['viewsearch']))
 {
 
     // Navigation bar
-    $step=$_SESSION['g_pagesize'];
+    $step=$_SESSION[SESSION_KEY.'g_pagesize'];
     $page=$http->get("page","number",1);
     $offset=$http->get("offset","number",0);
     
diff --git a/html/user_login.php b/html/user_login.php
index 0780af731..0b46a274d 100644
--- a/html/user_login.php
+++ b/html/user_login.php
@@ -29,7 +29,7 @@ require_once NOALYSS_INCLUDE.'/lib/http_input.class.php';
 require_once NOALYSS_INCLUDE.'/lib/function_javascript.php';
 require_once NOALYSS_INCLUDE.'/lib/icon_action.class.php';
 
-@html_page_start($_SESSION['g_theme']);
+@html_page_start($_SESSION[SESSION_KEY.'g_theme']);
 $rep=new Database();
 require_once NOALYSS_INCLUDE.'/class/user.class.php';
 $User=new User($rep);
diff --git a/include/admin_repo.inc.php b/include/admin_repo.inc.php
index a18e4ab0e..c20036014 100644
--- a/include/admin_repo.inc.php
+++ b/include/admin_repo.inc.php
@@ -60,7 +60,7 @@ if ( $action== 'backup') {
         require_once NOALYSS_INCLUDE."/backup.inc.php";
         exit();
 }
-html_page_start($_SESSION['g_theme']);
+html_page_start($_SESSION[SESSION_KEY.'g_theme']);
 load_all_script();
 echo '<H2 class="info"> '._('Administration').'</H2>';
 echo '<div class="topmenu">';
diff --git a/include/ajax/ajax_history.php b/include/ajax/ajax_history.php
index ffdb85ae4..2951e102e 100644
--- a/include/ajax/ajax_history.php
+++ b/include/ajax/ajax_history.php
@@ -36,7 +36,7 @@ $div=$http->request('div');
 mb_internal_encoding("UTF-8");
 $http=new HttpInput();
 /**
- *if $_SESSION['g_user'] is not set : echo a warning
+ *if $_SESSION[SESSION_KEY.'g_user'] is not set : echo a warning
  */
 /* security */
 if ( $g_user->check_dossier(dossier::id(),true) == 'X' ) exit();
diff --git a/include/ajax/ajax_ledger.php b/include/ajax/ajax_ledger.php
index 6eb4bcb09..40cd7c486 100644
--- a/include/ajax/ajax_ledger.php
+++ b/include/ajax/ajax_ledger.php
@@ -66,7 +66,7 @@ catch (Exception $exc)
 }
 
 /**
- *if $_SESSION['g_user'] is not set : echo a warning
+ *if $_SESSION[SESSION_KEY.'g_user'] is not set : echo a warning
  */
 
 $cn=Dossier::connect();
@@ -224,7 +224,7 @@ case 'file':
     $obj=$op->get_quant();	/* return an obj. ACH / FIN or VEN or null if nothing is found*/
     
     $repo = new Database();
-    $theme = $repo->get_value("select the_filestyle from theme where the_name=$1", array($_SESSION['g_theme']));
+    $theme = $repo->get_value("select the_filestyle from theme where the_name=$1", array($_SESSION[SESSION_KEY.'g_theme']));
     html_min_page_start($theme);
 
     // if there is a receipt document
@@ -317,7 +317,7 @@ case 'loadfile':
 
         echo "<html><head>";
         $repo=new Database();
-        $theme=$repo->get_value("select the_filestyle from theme where the_name=$1",array($_SESSION['g_theme']));
+        $theme=$repo->get_value("select the_filestyle from theme where the_name=$1",array($_SESSION[SESSION_KEY.'g_theme']));
         echo    "   <LINK REL=\"stylesheet\" type=\"text/css\" href=\"$theme\" media=\"screen\">";
         echo "</head>";
 		if ( ! isset($_REQUEST['ajax']) ) echo "<body class=\"op_detail_frame\">"; else echo "<body>";
@@ -347,7 +347,7 @@ case 'rmf':
     {
         echo "<html><head>";
         $repo=new Database();
-        $theme=$repo->get_value("select the_filestyle from theme where the_name=$1",array($_SESSION['g_theme']));
+        $theme=$repo->get_value("select the_filestyle from theme where the_name=$1",array($_SESSION[SESSION_KEY.'g_theme']));
         echo    "   <LINK REL=\"stylesheet\" type=\"text/css\" href=\"$theme\" media=\"screen\">";
         echo "</head><body class=\"op_detail_frame\">";
 		echo "<h2>"._("Document")."</h2>";
diff --git a/include/ajax/ajax_navigator.php b/include/ajax/ajax_navigator.php
index 757b37039..867c70885 100644
--- a/include/ajax/ajax_navigator.php
+++ b/include/ajax/ajax_navigator.php
@@ -34,7 +34,7 @@ $sql="
     where user_name=$1
     order by 2 ";
 
-$a_menu=$cn->get_array($sql,array($_SESSION['g_user']));
+$a_menu=$cn->get_array($sql,array($_SESSION[SESSION_KEY.'g_user']));
 
 ?>
 <div class="content">
diff --git a/include/ajax/ajax_preference.php b/include/ajax/ajax_preference.php
index f2eea8340..3f7448b60 100644
--- a/include/ajax/ajax_preference.php
+++ b/include/ajax/ajax_preference.php
@@ -59,7 +59,7 @@ if (isset($_REQUEST['gDossier']) && $http->request("gDossier","number",0) != 0 )
     $style->value = $repo->make_array("select the_name,the_name
 	from theme
 	order by the_name");
-    $style->selected =$_SESSION['g_theme'];
+    $style->selected =$_SESSION[SESSION_KEY.'g_theme'];
     
 //----------------------------------------------------------------------------------------------
 // Display the form    
@@ -164,8 +164,8 @@ if ( $action == 'display_form' )
     			    <option value="200">200
     			    <option value="-1"><?php echo _('Illimité');?>
 				    <?php
-				    $label = ($_SESSION['g_pagesize'] == -1) ? _('Illimité') : $_SESSION['g_pagesize'];
-				    echo '<option value="' . $_SESSION['g_pagesize'] . '" selected>' . $label;
+				    $label = ($_SESSION[SESSION_KEY.'g_pagesize'] == -1) ? _('Illimité') : $_SESSION[SESSION_KEY.'g_pagesize'];
+				    echo '<option value="' . $_SESSION[SESSION_KEY.'g_pagesize'] . '" selected>' . $label;
 				    ?>
     			</SELECT>
 
@@ -180,7 +180,7 @@ if ( $action == 'display_form' )
             <legend><?=_("Format Export CSV")?></legend>
             <p>
                 <?php 
-                if ( $_SESSION['csv_fieldsep']==1 && $_SESSION['csv_decimal']==1)
+                if ( $_SESSION[SESSION_KEY.'csv_fieldsep']==1 && $_SESSION[SESSION_KEY.'csv_decimal']==1)
                 {
                  echo_warning(_("N'utilisez pas le même séparateur pour les champs et les décimales"));
                 }
@@ -198,7 +198,7 @@ if ( $action == 'display_form' )
                                 ["label"=>_("Point-virgule"),"value"=>0],
                                 ["label"=>_("virgule"),"value"=>1]
                             ];
-                            $csv_fieldsep->selected=$_SESSION['csv_fieldsep'];
+                            $csv_fieldsep->selected=$_SESSION[SESSION_KEY.'csv_fieldsep'];
                             echo $csv_fieldsep->input();
                         ?>
                     </td>
@@ -214,7 +214,7 @@ if ( $action == 'display_form' )
                                 ["label"=>_("point"),"value"=>0],
                                 ["label"=>_("virgule"),"value"=>1]
                             ];
-                            $csv_decimal->selected=$_SESSION['csv_decimal'];
+                            $csv_decimal->selected=$_SESSION[SESSION_KEY.'csv_decimal'];
                             echo $csv_decimal->input();
                         ?>
                     </td>
@@ -230,7 +230,7 @@ if ( $action == 'display_form' )
                                 ["label"=>_("utf8"),"value"=>'utf8'],
                                 ["label"=>_("latin1"),"value"=>'latin1']
                             ];
-                            $csv_encoding->selected=$_SESSION['csv_encoding'];
+                            $csv_encoding->selected=$_SESSION[SESSION_KEY.'csv_encoding'];
                             echo $csv_encoding->input();
                         ?>
                     </td>
@@ -268,7 +268,7 @@ if ( $action == 'display_form' )
 	for ($i = 0; $i < count($aLang); $i++)
 	{
 	    $sel = "";
-	    if ($aLang[$i][1] == $_SESSION['g_lang'])
+	    if ($aLang[$i][1] == $_SESSION[SESSION_KEY.'g_lang'])
 		$sel = " selected ";
 	    printf('<option value="%s" %s>%s</option>', $aLang[$i][1], $sel, $aLang[$i][0]);
 	}
@@ -324,9 +324,9 @@ if ($action == 'save')
     $g_user->save_global_preference('csv_encoding', $csv_encoding);
     $g_user->save_email($p_email);
     
-    $_SESSION['g_theme']=$style_user;
-    $_SESSION['g_pagesize']=$p_size;
-    $_SESSION['g_lang']=$lang;
+    $_SESSION[SESSION_KEY.'g_theme']=$style_user;
+    $_SESSION[SESSION_KEY.'g_pagesize']=$p_size;
+    $_SESSION[SESSION_KEY.'g_lang']=$lang;
     
     // find the right CSS theme
     $style= $repo->get_value("select the_filestyle from theme
diff --git a/include/ajax/ajax_todo_list.php b/include/ajax/ajax_todo_list.php
index 3b129bbab..0805569dc 100644
--- a/include/ajax/ajax_todo_list.php
+++ b/include/ajax/ajax_todo_list.php
@@ -102,7 +102,7 @@ if ($ac == 'save')
     if ($id <> 0 ) { $todo->load(); }
     else
     {
-        $todo->set_parameter("owner", $_SESSION['g_user']);
+        $todo->set_parameter("owner", $_SESSION[SESSION_KEY.'g_user']);
     }
     
     $todo->set_parameter("date",$http->post("p_date_todo","string", ""));
@@ -111,7 +111,7 @@ if ($ac == 'save')
     $todo->set_is_public($http->post("p_public", "string","N"));
     
     ob_start();
-    if ( $todo->get_parameter('owner') == $_SESSION['g_user'] ) $todo->save();
+    if ( $todo->get_parameter('owner') == $_SESSION[SESSION_KEY.'g_user'] ) $todo->save();
     ob_end_clean();
     $dom=new DOMDocument('1.0','UTF-8');
     
diff --git a/include/class/acc_ledger.class.php b/include/class/acc_ledger.class.php
index 003513bc2..995423a5f 100644
--- a/include/class/acc_ledger.class.php
+++ b/include/class/acc_ledger.class.php
@@ -2016,8 +2016,8 @@ class Acc_Ledger  extends jrn_def_sql
             echo Acc_Reconciliation::$javascript;
             html_page_start();
             $cn=Dossier::connect();
-            $_SESSION['g_user']=NOALYSS_ADMINISTRATOR;
-            $_SESSION['g_pass']='phpcompta';
+            $_SESSION[SESSION_KEY.'g_user']=NOALYSS_ADMINISTRATOR;
+            $_SESSION[SESSION_KEY.'g_pass']='phpcompta';
 
             $id=(isset($_REQUEST['p_jrn']))?$_REQUEST['p_jrn']:-1;
             $a=new Acc_Ledger($cn, $id);
@@ -2109,8 +2109,8 @@ class Acc_Ledger  extends jrn_def_sql
             html_page_start();
             $cn=Dossier::connect();
             $ledger=new Acc_Ledger($cn, 0);
-            $_SESSION['g_user']=NOALYSS_ADMINISTRATOR;
-            $_SESSION['g_pass']='phpcompta';
+            $_SESSION[SESSION_KEY.'g_user']=NOALYSS_ADMINISTRATOR;
+            $_SESSION[SESSION_KEY.'g_pass']='phpcompta';
             echo $ledger->search_form('ALL');
         }
         ///////////////////////////////////////////////////////////////////////////
diff --git a/include/class/acc_ledger_purchase.class.php b/include/class/acc_ledger_purchase.class.php
index 241744697..39f3c5549 100644
--- a/include/class/acc_ledger_purchase.class.php
+++ b/include/class/acc_ledger_purchase.class.php
@@ -1788,7 +1788,7 @@ EOF;
         // Show list of unpaid sell
         // Date - date of payment - Customer - amount
         // Nav. bar
-        $step=$_SESSION['g_pagesize'];
+        $step=$_SESSION[SESSION_KEY.'g_pagesize'];
         $page=(isset($_GET['offset']))?$_GET['page']:1;
         $offset=(isset($_GET['offset']))?$_GET['offset']:0;
 
diff --git a/include/class/acc_ledger_search.class.php b/include/class/acc_ledger_search.class.php
index 4989f61e6..b435c8dc3 100644
--- a/include/class/acc_ledger_search.class.php
+++ b/include/class/acc_ledger_search.class.php
@@ -639,7 +639,7 @@ class Acc_Ledger_Search
             
             $fil_sec=$and." jr_def_id in ( select uj_jrn_id ".
                     " from user_sec_jrn where ".
-                    " uj_login='".sql_string($_SESSION['g_user'])."'".
+                    " uj_login='".sql_string($_SESSION[SESSION_KEY.'g_user'])."'".
                     " and uj_priv in ('R','W'))";
         }
         $where=$fil_ledger.$fil_amount.$fil_date.$fil_desc.$fil_sec.$fil_amount.
@@ -712,7 +712,7 @@ class Acc_Ledger_Search
       // Count nb of line
       $max_line=$cn->count_sql($sql);
 
-      $step=$_SESSION['g_pagesize'];
+      $step=$_SESSION[SESSION_KEY.'g_pagesize'];
       $page=(isset($_GET['offset']))?$_GET['page']:1;
       $offset=(isset($_GET['offset']))?$_GET['offset']:0;
       // create the nav. bar
@@ -738,8 +738,8 @@ class Acc_Ledger_Search
         $gDossier=dossier::id();
         $amount_paid=0.0;
         $amount_unpaid=0.0;
-        $limit=($_SESSION['g_pagesize']!=-1)?" LIMIT ".$_SESSION['g_pagesize']:"";
-        $offset=($_SESSION['g_pagesize']!=-1)?" OFFSET ".Database::escape_string($offset):"";
+        $limit=($_SESSION[SESSION_KEY.'g_pagesize']!=-1)?" LIMIT ".$_SESSION[SESSION_KEY.'g_pagesize']:"";
+        $offset=($_SESSION[SESSION_KEY.'g_pagesize']!=-1)?" OFFSET ".Database::escape_string($offset):"";
         $order="  order by jr_date_order asc,jr_internal asc";
         // Sort
         $url="?".CleanUrl();
@@ -1011,7 +1011,7 @@ class Acc_Ledger_Search
       // Count nb of line
       $max_line=$this->cn->count_sql($sql);
 
-      $step=$_SESSION['g_pagesize'];
+      $step=$_SESSION[SESSION_KEY.'g_pagesize'];
       $page=(isset($_GET['offset']))?$_GET['page']:1;
       $offset=(isset($_GET['offset']))?$_GET['offset']:0;
       // create the nav. bar
diff --git a/include/class/acc_operation.class.php b/include/class/acc_operation.class.php
index 06946c760..fd30cf612 100644
--- a/include/class/acc_operation.class.php
+++ b/include/class/acc_operation.class.php
@@ -56,7 +56,7 @@ class Acc_Operation
         global $g_user;
         $this->db=$p_cn;
         $this->qcode="";
-        $this->user=$_SESSION['g_user'];
+        $this->user=$_SESSION[SESSION_KEY.'g_user'];
         $this->periode=$g_user->get_periode();
         $this->jr_id=0;
         $this->jr_optype="NOR";
@@ -700,8 +700,8 @@ class Acc_Operation
     }
     static function test_me()
     {
-        $_SESSION['g_user']=NOALYSS_ADMINISTRATOR;
-        $_SESSION['g_pass']='dany';
+        $_SESSION[SESSION_KEY.'g_user']=NOALYSS_ADMINISTRATOR;
+        $_SESSION[SESSION_KEY.'g_pass']='dany';
         global $g_user;
         $cn=Dossier::connect();
         $g_user=new User($cn);
diff --git a/include/class/anc_operation.class.php b/include/class/anc_operation.class.php
index f8c2ea835..35b8f4e78 100644
--- a/include/class/anc_operation.class.php
+++ b/include/class/anc_operation.class.php
@@ -274,7 +274,7 @@ class Anc_Operation
             return _("Pas d'enregistrement trouvé");
 
         // navigation_bar
-        $step=$_SESSION['g_pagesize'];
+        $step=$_SESSION[SESSION_KEY.'g_pagesize'];
         $page=(isset($_GET['offset']))?$_GET['page']:1;
         $offset=(isset($_GET['offset']))?$_GET['offset']:0;
         $bar=navigation_bar($offset+1,count($array),$step,$page);
diff --git a/include/class/calendar.class.php b/include/class/calendar.class.php
index 643e5e2ea..58aa9e149 100644
--- a/include/class/calendar.class.php
+++ b/include/class/calendar.class.php
@@ -129,7 +129,7 @@ class Calendar
                  " to_char(tl_date,'MM')::integer=$1 ".
                  " and to_char(tl_date,'YYYY')::integer=$2 ".
                  " and use_login=$3 group by to_char(tl_date,'DD')::integer ";
-            $array=$cn->get_array($sql,array($this->month,$this->year,$_SESSION['g_user']));
+            $array=$cn->get_array($sql,array($this->month,$this->year,$_SESSION[SESSION_KEY.'g_user']));
             for ($i=0;$i<count($array);$i++)
             {
                 $ind=$array[$i]['tl_date_day'];
@@ -143,7 +143,7 @@ class Calendar
                  " to_char(tl_date,'MM')::integer=$1 ".
                  " and to_char(tl_date,'YYYY')::integer=$2 ".
                  " and use_login=$3  ";
-            $array=$cn->get_array($sql,array($this->month,$this->year,$_SESSION['g_user']));
+            $array=$cn->get_array($sql,array($this->month,$this->year,$_SESSION[SESSION_KEY.'g_user']));
             for ($i=0;$i<count($array);$i++)
             {
                 $ind=$array[$i]['tl_date_day'];
diff --git a/include/class/contact.class.php b/include/class/contact.class.php
index 39bf44953..9efb99340 100644
--- a/include/class/contact.class.php
+++ b/include/class/contact.class.php
@@ -63,7 +63,7 @@ class contact extends Fiche
         // Get offset and page variable
         $offset=( isset ($_REQUEST['offset'] )) ?$_REQUEST['offset']:0;
         $page=(isset($_REQUEST['page']))?$_REQUEST['page']:1;
-        $bar=navigation_bar($offset,$all_contact,$_SESSION['g_pagesize'],$page);
+        $bar=navigation_bar($offset,$all_contact,$_SESSION[SESSION_KEY.'g_pagesize'],$page);
         // set a filter ?
         $search="";
         if ( trim($p_search) != "" )
diff --git a/include/class/document.class.php b/include/class/document.class.php
index d7b7f8789..e75d09051 100644
--- a/include/class/document.class.php
+++ b/include/class/document.class.php
@@ -822,7 +822,7 @@ class Document
             break;
 
         case 'USER' :
-            return $_SESSION['use_name'].', '.$_SESSION['use_first_name'];
+            return $_SESSION[SESSION_KEY.'use_name'].', '.$_SESSION[SESSION_KEY.'use_first_name'];
 
             break;
         case 'REFERENCE':
diff --git a/include/class/extension.class.php b/include/class/extension.class.php
index 1b321fe60..31961e436 100644
--- a/include/class/extension.class.php
+++ b/include/class/extension.class.php
@@ -97,7 +97,7 @@ class Extension extends Menu_Ref_sql
                 " menu_ref join profile_menu using (me_code)
 				 join profile_user using (p_id) where ".
                 " user_name=$1 and me_type='PL' ORDER BY ME_MENU";
-        $a=$cn->get_array($sql, array($_SESSION['g_user']));
+        $a=$cn->get_array($sql, array($_SESSION[SESSION_KEY.'g_user']));
         return $a;
     }
 
diff --git a/include/class/fiche.class.php b/include/class/fiche.class.php
index 5bbd6fe9f..631e24c51 100644
--- a/include/class/fiche.class.php
+++ b/include/class/fiche.class.php
@@ -303,7 +303,7 @@ class Fiche
         }
         else
         {
-            $limit=($_SESSION['g_pagesize']!=-1)?"limit ".$_SESSION['g_pagesize']:"";
+            $limit=($_SESSION[SESSION_KEY.'g_pagesize']!=-1)?"limit ".$_SESSION[SESSION_KEY.'g_pagesize']:"";
             $sql="select *
                  from
                  fiche join fiche_Def using (fd_id) join vw_fiche_name using(f_id)
@@ -1776,7 +1776,7 @@ class Fiche
         // Get offset and page variable
         $offset=( isset ($_REQUEST['offset'] )) ?$_REQUEST['offset']:0;
         $page=(isset($_REQUEST['page']))?$_REQUEST['page']:1;
-        $bar=navigation_bar($offset,$all_tiers,$_SESSION['g_pagesize'],$page);
+        $bar=navigation_bar($offset,$all_tiers,$_SESSION[SESSION_KEY.'g_pagesize'],$page);
 
         // set a filter ?
         $search=$p_sql;
diff --git a/include/class/fiche_def.class.php b/include/class/fiche_def.class.php
index a06ee60f6..ddae639a1 100644
--- a/include/class/fiche_def.class.php
+++ b/include/class/fiche_def.class.php
@@ -324,10 +324,10 @@ $order
              where ad_id=1 and fd_id=$1 order by 2";
 
         // we use navigation_bar
-        if ($step == 1  && $_SESSION['g_pagesize'] != -1   )
+        if ($step == 1  && $_SESSION[SESSION_KEY.'g_pagesize'] != -1   )
         {
             $offset=(isset($_GET['offset']))?$_GET['offset']:0;
-            $step=$_SESSION['g_pagesize'];
+            $step=$_SESSION[SESSION_KEY.'g_pagesize'];
             $sql.=" offset $offset limit $step";
         }
 
@@ -370,7 +370,7 @@ $order
         $this->get();
         echo '<H2 class="info">'.$this->id." ".$this->label.'</H2>';
 
-        $step=$_SESSION['g_pagesize'];
+        $step=$_SESSION[SESSION_KEY.'g_pagesize'];
         $sql_limit="";
         $sql_offset="";
         $bar="";
@@ -398,7 +398,7 @@ $order
         $str="";
         // save the url
         // with offet &offset=15&step=15&page=2&size=15
-        if ( $_SESSION['g_pagesize'] != -1)
+        if ( $_SESSION[SESSION_KEY.'g_pagesize'] != -1)
         {
             $str=sprintf("&offset=%s&step=%s&page=%s&size=%s",
                          $offset,
diff --git a/include/class/follow_up.class.php b/include/class/follow_up.class.php
index 9c78f7115..7a57316ee 100644
--- a/include/class/follow_up.class.php
+++ b/include/class/follow_up.class.php
@@ -577,7 +577,7 @@ class Follow_Up
             $this->ag_dest, /* 7 */
             $this->ag_hour, /* 8 */
             $this->ag_priority, /* 9 */
-            $_SESSION['g_user'], /* 10 */
+            $_SESSION[SESSION_KEY.'g_user'], /* 10 */
             $contact->id, /* 11 */
             $this->ag_state, /* 12 */
             $this->ag_remind_date /* 13 */
@@ -602,12 +602,12 @@ class Follow_Up
         if (trim($this->ag_comment)!='' && Document_Option::can_add_comment($this->ag_id))
         {
             $this->db->exec_sql("insert into action_gestion_comment (ag_id,tech_user,agc_comment) values ($1,$2,$3)"
-                , array($this->ag_id, $_SESSION['g_user'], $this->ag_comment));
+                , array($this->ag_id, $_SESSION[SESSION_KEY.'g_user'], $this->ag_comment));
         }
         if (trim($this->ag_description)!='' && Document_Option::can_add_comment($this->ag_id))
         {
             $this->db->exec_sql("insert into action_gestion_comment (ag_id,tech_user,agc_comment) values ($1,$2,$3)"
-                , array($this->ag_id, $_SESSION['g_user'], $this->ag_description));
+                , array($this->ag_id, $_SESSION[SESSION_KEY.'g_user'], $this->ag_description));
         }
         $this->insert_operation();
         $this->insert_action();
@@ -672,7 +672,7 @@ class Follow_Up
                 join document_state on (ag_state=s_id)
              where $p_filter_doc $p_search $sort";
         $max_line=$this->db->count_sql($sql);
-        $step=$_SESSION['g_pagesize'];
+        $step=$_SESSION[SESSION_KEY.'g_pagesize'];
         $page=(isset($_GET['offset']))?$_GET['page']:1;
         $offset=(isset($_GET['offset']))?Database::escape_string($_GET['offset']):0;
         if ($step!=-1)
@@ -925,12 +925,12 @@ class Follow_Up
         if (trim($this->ag_comment)!='')
         {
             $this->db->exec_sql("insert into action_gestion_comment (ag_id,tech_user,agc_comment) values ($1,$2,$3)"
-                    , array($this->ag_id, $_SESSION['g_user'], $this->ag_comment));
+                    , array($this->ag_id, $_SESSION[SESSION_KEY.'g_user'], $this->ag_comment));
         }
         if (trim($this->ag_description)!='')
         {
             $this->db->exec_sql("insert into action_gestion_comment (ag_id,tech_user,agc_comment) values ($1,$2,$3)"
-                    , array($this->ag_id, $_SESSION['g_user'], $this->ag_description));
+                    , array($this->ag_id, $_SESSION[SESSION_KEY.'g_user'], $this->ag_description));
         }
         $this->insert_operation();
         $this->insert_action();
@@ -1355,11 +1355,11 @@ class Follow_Up
         {
             $action_query.= " and ((ag_dest = ".sql_string($p_array['ag_dest_query'])." and ".self::sql_security_filter($cn, "R").") or ".
                     "(ag_dest = ".sql_string($p_array['ag_dest_query'])." and ".self::sql_security_filter($cn, "R")." and ".
-                    " ag_owner='".$_SESSION['g_user']."'))";
+                    " ag_owner='".$_SESSION[SESSION_KEY.'g_user']."'))";
         }
         else
         {
-            $action_query .=" and (ag_owner='".$_SESSION['g_user']."' or ".self::sql_security_filter($cn, "R")." or ag_dest=-1 )";
+            $action_query .=" and (ag_owner='".$_SESSION[SESSION_KEY.'g_user']."' or ".self::sql_security_filter($cn, "R")." or ag_dest=-1 )";
         }
 
 
@@ -1744,7 +1744,7 @@ class Follow_Up
             $ag_ref, /* 6 */
             $this->ag_dest, /* 7 */
             $this->ag_priority, /* 8 */
-            $_SESSION['g_user'], /* 9 */
+            $_SESSION[SESSION_KEY.'g_user'], /* 9 */
             $this->ag_state, /* 10 */
             $this->ag_remind_date, /* 11 */
             $this->ag_hour /* 12 */
@@ -1754,7 +1754,7 @@ class Follow_Up
         if (trim($this->ag_comment)!='')
         {
             $this->db->exec_sql("insert into action_gestion_comment (ag_id,tech_user,agc_comment) values ($1,$2,$3)"
-                    , array($this->ag_id, $_SESSION['g_user'], $this->ag_comment));
+                    , array($this->ag_id, $_SESSION[SESSION_KEY.'g_user'], $this->ag_comment));
         }
     }
     /**
diff --git a/include/class/stock.class.php b/include/class/stock.class.php
index dcd58ad16..e4ceb8df6 100644
--- a/include/class/stock.class.php
+++ b/include/class/stock.class.php
@@ -55,7 +55,7 @@ class Stock extends Stock_Sql
 		$order = (isset($p_array['ord'])) ? $p_array['ord'] : 'da';
 
 		$sql.=$tb->get_sql_order($order);
-		$step = $_SESSION['g_pagesize'];
+		$step = $_SESSION[SESSION_KEY.'g_pagesize'];
 		$page = (isset($_GET['offset'])) ? $_GET['page'] : 1;
 		$offset = (isset($_GET['offset'])) ? $_GET['offset'] : 0;
 
diff --git a/include/class/stock_goods.class.php b/include/class/stock_goods.class.php
index 8ffd0b453..899eecf79 100644
--- a/include/class/stock_goods.class.php
+++ b/include/class/stock_goods.class.php
@@ -126,7 +126,7 @@ class Stock_Goods extends Stock_Goods_Sql
 			$ch->setp("c_comment", $p_array['p_motif']);
 			$ch->setp("r_id", $p_array['p_depot']);
 			$ch->setp("c_date", $p_array['p_date']);
-			$ch->setp('tech_user', $_SESSION['g_user']);
+			$ch->setp('tech_user', $_SESSION[SESSION_KEY.'g_user']);
 			$ch->insert();
 			$per = new Periode($cn);
 			$periode = $per->find_periode($p_array['p_date']);
@@ -154,7 +154,7 @@ class Stock_Goods extends Stock_Goods_Sql
 					$a->sg_quantity = abs($p_array['sg_quantity' . $i]);
 					$a->sg_type = ($p_array['sg_quantity' . $i] > 0) ? 'd' : 'c';
 					$a->sg_comment = $p_array['p_motif'];
-					$a->tech_user = $_SESSION['g_user'];
+					$a->tech_user = $_SESSION[SESSION_KEY.'g_user'];
 					$a->r_id = $p_array['p_depot'];
 					$a->sg_exercice = $exercice;
 					$a->c_id = $ch->c_id;
diff --git a/include/class/todo_list.class.php b/include/class/todo_list.class.php
index e759a3adb..d42747ea7 100644
--- a/include/class/todo_list.class.php
+++ b/include/class/todo_list.class.php
@@ -57,7 +57,7 @@ class Todo_List
         $this->cn=$p_init;
         $this->tl_id=0;
         $this->tl_desc="";
-        $this->use_login=$_SESSION['g_user'];
+        $this->use_login=$_SESSION[SESSION_KEY.'g_user'];
         $this->is_public="N";
 
     }
@@ -228,7 +228,7 @@ class Todo_List
     public function delete()
     {
         global $g_user;
-        if ( $this->use_login != $_SESSION['g_user'] && $g_user->check_action(SHARENOTEREMOVE)==0) return;
+        if ( $this->use_login != $_SESSION[SESSION_KEY.'g_user'] && $g_user->check_action(SHARENOTEREMOVE)==0) return;
         
         $sql="delete from todo_list_shared where todo_list_id=$1 ";
         $res=$this->cn->exec_sql($sql,array($this->tl_id));
@@ -329,11 +329,11 @@ class Todo_List
       htmlspecialchars($this->tl_title).
       '</a>'.
        '</td>';
-        if ( $this->is_public == 'Y' && $this->use_login != $_SESSION['g_user'] )
+        if ( $this->is_public == 'Y' && $this->use_login != $_SESSION[SESSION_KEY.'g_user'] )
         { // This is a public note, cannot be removed
             $r.= '<td></td>';
         }
-        elseif ($this->use_login == $_SESSION['g_user'] )
+        elseif ($this->use_login == $_SESSION[SESSION_KEY.'g_user'] )
         {
             // This a note the user owns
             $r.=  '<td>'.
diff --git a/include/class/user.class.php b/include/class/user.class.php
index 7ea928d27..2190bb048 100644
--- a/include/class/user.class.php
+++ b/include/class/user.class.php
@@ -53,28 +53,28 @@ class User
 		// if p_id is not set then check the connected user
 		if ($p_id == -1)
 		{
-			if (!isset($_SESSION['g_user']))
+			if (!isset($_SESSION[SESSION_KEY.'g_user']))
 			{
 				echo '<h2 class="error">' . _('Session expirée<br>Utilisateur déconnecté') . '</h2>';
 				redirect('index.php', 1);
 				exit();
 			}
 
-			$this->login =strtolower($_SESSION['g_user']);
-			$this->pass = $_SESSION['g_pass'];
-			$this->lang = (isset($_SESSION['g_lang'])) ? $_SESSION['g_lang'] : 'fr_FR.utf8';
-			$this->valid = (isset($_SESSION['isValid'])) ? 1 : 0;
+			$this->login =strtolower($_SESSION[SESSION_KEY.'g_user']);
+			$this->pass = $_SESSION[SESSION_KEY.'g_pass'];
+			$this->lang = (isset($_SESSION[SESSION_KEY.'g_lang'])) ? $_SESSION[SESSION_KEY.'g_lang'] : 'fr_FR.utf8';
+			$this->valid = (isset($_SESSION[SESSION_KEY.'isValid'])) ? 1 : 0;
 			$this->db = $p_cn;
 			$this->id = -1;
-			if (isset($_SESSION['g_theme']))
-				$this->theme = $_SESSION['g_theme'];
+			if (isset($_SESSION[SESSION_KEY.'g_theme']))
+				$this->theme = $_SESSION[SESSION_KEY.'g_theme'];
 
-			$this->admin = ( isset($_SESSION['use_admin']) ) ? $_SESSION['use_admin'] : 0;
+			$this->admin = ( isset($_SESSION[SESSION_KEY.'use_admin']) ) ? $_SESSION[SESSION_KEY.'use_admin'] : 0;
 
-			if (isset($_SESSION['use_name']))
-				$this->name = $_SESSION['use_name'];
-			if (isset($_SESSION['use_first_name']))
-				$this->first_name = $_SESSION['use_first_name'];
+			if (isset($_SESSION[SESSION_KEY.'use_name']))
+				$this->name = $_SESSION[SESSION_KEY.'use_name'];
+			if (isset($_SESSION[SESSION_KEY.'use_first_name']))
+				$this->first_name = $_SESSION[SESSION_KEY.'use_first_name'];
 			$this->load();
 		}
 		else // if p_id is set get data of another user
@@ -176,21 +176,21 @@ class User
 		if ($res > 0)
 		{
 			$r = Database::fetch_array($ret, 0);
-			$_SESSION['use_admin'] = $r['use_admin'];
-			$_SESSION['use_name'] = $r['use_name'];
-			$_SESSION['use_first_name'] = $r['use_first_name'];
-			$_SESSION['isValid'] = 1;
+			$_SESSION[SESSION_KEY.'use_admin'] = $r['use_admin'];
+			$_SESSION[SESSION_KEY.'use_name'] = $r['use_name'];
+			$_SESSION[SESSION_KEY.'use_first_name'] = $r['use_first_name'];
+			$_SESSION[SESSION_KEY.'isValid'] = 1;
 
-			$this->admin = $_SESSION['use_admin'];
-			$this->name = $_SESSION['use_name'];
-			$this->first_name = $_SESSION['use_first_name'];
+			$this->admin = $_SESSION[SESSION_KEY.'use_admin'];
+			$this->name = $_SESSION[SESSION_KEY.'use_name'];
+			$this->first_name = $_SESSION[SESSION_KEY.'use_first_name'];
 			$this->load_global_pref();
 		}
 		$sql = "insert into audit_connect (ac_user,ac_ip,ac_module,ac_url,ac_state) values ($1,$2,$3,$4,$5)";
 
 		if ($res == 0)
 		{
-			$cn->exec_sql($sql, array($_SESSION['g_user'], $_SERVER["REMOTE_ADDR"], $from, $_SERVER['REQUEST_URI'], 'FAIL'));
+			$cn->exec_sql($sql, array($_SESSION[SESSION_KEY.'g_user'], $_SERVER["REMOTE_ADDR"], $from, $_SERVER['REQUEST_URI'], 'FAIL'));
 			if (!$silent)
 			{
 				echo '<script> alert(\''._('Utilisateur ou mot de passe incorrect').'\')</script>';
@@ -203,7 +203,7 @@ class User
 		else
 		{
 			if ($from == 'LOGIN')
-				$cn->exec_sql($sql, array($_SESSION['g_user'], $_SERVER["REMOTE_ADDR"], $from, $_SERVER['REQUEST_URI'], 'SUCCESS'));
+				$cn->exec_sql($sql, array($_SESSION[SESSION_KEY.'g_user'], $_SERVER["REMOTE_ADDR"], $from, $_SERVER['REQUEST_URI'], 'SUCCESS'));
 			$this->valid = 1;
 		}
 
@@ -597,7 +597,7 @@ class User
 			{
 				$cn = new Database();
 				$sql = "insert into audit_connect (ac_user,ac_ip,ac_module,ac_url,ac_state) values ($1,$2,$3,$4,$5)";
-				$cn->exec_sql($sql, array($_SESSION['g_user'], $_SERVER["REMOTE_ADDR"], $p_action_id, $_SERVER['REQUEST_URI'], 'FAIL'));
+				$cn->exec_sql($sql, array($_SESSION[SESSION_KEY.'g_user'], $_SERVER["REMOTE_ADDR"], $p_action_id, $_SERVER['REQUEST_URI'], 'FAIL'));
 			}
 			return 0;
 		}
@@ -654,7 +654,7 @@ class User
 				$this->load_global_pref();
 				return;
 			}
-			$_SESSION[$name] = $line[$parameter];
+			$_SESSION[SESSION_KEY.$name] = $line[$parameter];
 		}
 	}
 
@@ -1094,7 +1094,7 @@ class User
 		$sql = "insert into audit_connect (ac_user,ac_ip,ac_module,ac_url,ac_state) values ($1,$2,$3,$4,$5)";
 
 		$cn->exec_sql($sql, array(
-			$_SESSION['g_user'],
+			$_SESSION[SESSION_KEY.'g_user'],
 			$_SERVER["REMOTE_ADDR"],
 			$p_module,
 			$_SERVER['REQUEST_URI'],
@@ -1115,7 +1115,7 @@ class User
 			$sql = "insert into audit_connect (ac_user,ac_ip,ac_module,ac_url,ac_state) values ($1,$2,$3,$4,$5)";
 
 			$cn->exec_sql($sql, array(
-				$_SESSION['g_user'],
+				$_SESSION[SESSION_KEY.'g_user'],
 				$_SERVER["REMOTE_ADDR"],
 				$p_module,
 				$_SERVER['REQUEST_URI'],
@@ -1293,8 +1293,8 @@ class User
         if ($p_pass1 == $p_pass2) {
             $repo = new Database();
             $l_pass = md5($_POST['pass_1']);
-            $repo->exec_sql("update ac_users set use_pass=$1 where use_login=$2", array($l_pass, $_SESSION['g_user']));
-            $_SESSION['g_pass'] = $_POST['pass_1'];
+            $repo->exec_sql("update ac_users set use_pass=$1 where use_login=$2", array($l_pass, $_SESSION[SESSION_KEY.'g_user']));
+            $_SESSION[SESSION_KEY.'g_pass'] = $_POST['pass_1'];
         } else {
             alert(_("Les mots de passe ne correspondent pas. Mot de passe inchangé"));
         }
@@ -1306,7 +1306,7 @@ class User
     function save_email($p_email)
     {
         $repo=new Database();
-        $repo->exec_sql("update ac_users set use_email=$1 where use_login=$2", array($p_email, $_SESSION['g_user']));
+        $repo->exec_sql("update ac_users set use_email=$1 where use_login=$2", array($p_email, $_SESSION[SESSION_KEY.'g_user']));
     }
     /**
      * Remove a user and all his privileges
diff --git a/include/config.inc.example b/include/config.inc.example
index 65650be22..e1be7d1be 100644
--- a/include/config.inc.example
+++ b/include/config.inc.example
@@ -69,4 +69,6 @@ define ("dbname","");
 // In recent distribution linux, pdftk is a snap, you should set the path
 // for exporting document in PDF
 // $pdftk = /usr/bin/pdftk 
-// $pdftk = /snap/bin/pdftk 
+// $pdftk = /snap/bin/pdftk
+// Define a random session key if you work with different version of NOALYSS
+// define ('SESSION_KEY','abcde');
diff --git a/include/constant.php b/include/constant.php
index 5aa3a4da6..feaf0812c 100644
--- a/include/constant.php
+++ b/include/constant.php
@@ -51,7 +51,9 @@ if ( !defined("FIX_BROKEN_PDF")) define ("FIX_BROKEN_PDF",'NO');
 if ( !defined('NOALYSS_ADMINISTRATOR')) {
     define ('NOALYSS_ADMINISTRATOR','phpcompta');
 }
-
+if (!defined ("SESSION_KEY")) {
+    define ("SESSION_KEY","RtYu0uu");
+}
 require_once NOALYSS_INCLUDE.'/constant.security.php';
 
 if ( strpos($inc_path,";") != 0 ) {
diff --git a/include/extension_choice.inc.php b/include/extension_choice.inc.php
index afca41139..ba5a2484e 100644
--- a/include/extension_choice.inc.php
+++ b/include/extension_choice.inc.php
@@ -14,7 +14,7 @@ require_once NOALYSS_INCLUDE.'/lib/iselect.class.php';
 require_once  NOALYSS_INCLUDE.'/constant.security.php';
 require_once  NOALYSS_INCLUDE.'/class/user.class.php';
 echo '<div class="topmenu">';
-@html_page_start($_SESSION['g_theme']);
+@html_page_start($_SESSION[SESSION_KEY.'g_theme']);
 
 $cn=Dossier::connect();
 global $g_user;
diff --git a/include/fiche.inc.php b/include/fiche.inc.php
index 91fa20bdb..39f118988 100644
--- a/include/fiche.inc.php
+++ b/include/fiche.inc.php
@@ -206,7 +206,7 @@ if ($histo->selected   == -1)
 	// Create nav bar
 	$max = $cn->get_value("select count(*) from fiche as f " . $cond);
 
-	$step = $_SESSION['g_pagesize'];
+	$step = $_SESSION[SESSION_KEY.'g_pagesize'];
 	$page = (isset($_GET['offset'])) ? $_GET['page'] : 1;
 	$offset = (isset($_GET['offset'])) ? $_GET['offset'] : 0;
 	$bar = navigation_bar($offset, $max, $step, $page);
diff --git a/include/history_operation.inc.php b/include/history_operation.inc.php
index d61658e67..ed6f5168b 100644
--- a/include/history_operation.inc.php
+++ b/include/history_operation.inc.php
@@ -107,7 +107,7 @@ else
 list($sql, $where) = $Ledger->build_search_sql($p_array);
 $max_line = $cn->count_sql($sql);
 
-$step = $_SESSION['g_pagesize'];
+$step = $_SESSION[SESSION_KEY.'g_pagesize'];
 $page = (isset($_GET['offset'])) ? $http->get('page') : 1;
 $offset = (isset($_GET['offset'])) ? $http->get('offset') : 0;
 
diff --git a/include/lib/ac_common.php b/include/lib/ac_common.php
index c6c30e7d1..71e85fba2 100644
--- a/include/lib/ac_common.php
+++ b/include/lib/ac_common.php
@@ -344,11 +344,11 @@ function html_page_start($p_theme="", $p_script="", $p_script2="")
     echo '<script language="javascript" src="js/calendar.js"></script>
     <script type="text/javascript" src="js/lang/calendar-en.js"></script>';
 
-    if (isset($_SESSION['g_lang']) && $_SESSION['g_lang']=='fr_FR.utf8' )
+    if (isset($_SESSION[SESSION_KEY.'g_lang']) && $_SESSION[SESSION_KEY.'g_lang']=='fr_FR.utf8' )
     {
 	echo '<script type="text/javascript" src="js/lang/calendar-fr.js"></script>';
     }
-    if (isset($_SESSION['g_lang']) && $_SESSION['g_lang']=='nl_NL.utf8' )
+    if (isset($_SESSION[SESSION_KEY.'g_lang']) && $_SESSION[SESSION_KEY.'g_lang']=='nl_NL.utf8' )
     {
 	echo '<script type="text/javascript" src="js/lang/calendar-nl.js"></script>';
     }
@@ -357,7 +357,7 @@ function html_page_start($p_theme="", $p_script="", $p_script2="")
     <LINK REL="stylesheet" type="text/css" href="calendar-blue.css" media="screen">
     ';
     // language
-    if (isset($_SESSION['g_lang']))
+    if (isset($_SESSION[SESSION_KEY.'g_lang']))
     {
 		set_language();
     }
@@ -710,7 +710,7 @@ function set_language()
 {
     // desactivate local check
     if ( defined("LOCALE") && LOCALE==0 ) return;
-    if ( ! isset ($_SESSION['g_lang'])) return;
+    if ( ! isset ($_SESSION[SESSION_KEY.'g_lang'])) return;
     
     /*
      * If translation is not supported by current
@@ -721,12 +721,12 @@ function set_language()
     // set differently the language depending of the operating system
     if (what_os() == 1)
     {
-	$dir = setlocale(LC_MESSAGES, $_SESSION['g_lang']);
+	$dir = setlocale(LC_MESSAGES, $_SESSION[SESSION_KEY.'g_lang']);
 	if ($dir == "")
 	{
 	    $g_lang = 'fr_FR.utf8';
 	    $dir = setlocale(LC_MESSAGES, $g_lang);
-	   // echo '<span class="notice">' . $_SESSION['g_lang'] . ' domaine non supporté</h2>';
+	   // echo '<span class="notice">' . $_SESSION[SESSION_KEY.'g_lang'] . ' domaine non supporté</h2>';
 	}
 	bindtextdomain('messages', NOALYSS_HOME.'/lang');
 	textdomain('messages');
@@ -735,8 +735,8 @@ function set_language()
 	return;
     }
     // for windows
-    putenv('LANG=' . $_SESSION['g_lang']);
-    $dir = setlocale(LC_ALL, $_SESSION['g_lang']);
+    putenv('LANG=' . $_SESSION[SESSION_KEY.'g_lang']);
+    $dir = setlocale(LC_ALL, $_SESSION[SESSION_KEY.'g_lang']);
     bindtextdomain('messages', '.\\lang');
     textdomain('messages');
     bind_textdomain_codeset('messages', 'UTF8');
@@ -851,9 +851,9 @@ function format_date($p_date, $p_from_format = 'YYYY-MM-DD',$p_to_format='DD.MM.
 function ajax_disconnected($div)
 {
     /**
-     * if $_SESSION['g_user'] is not set : echo a warning
+     * if $_SESSION[SESSION_KEY.'g_user'] is not set : echo a warning
      */
-    if (!isset($_SESSION['g_user']))
+    if (!isset($_SESSION[SESSION_KEY.'g_user']))
     {
 	$script = 'var a=$("' . $div . '");a.style.height="70%";a.style.width="60%";';
 	$script.='a.style.top=posY-20+offsetY;a.style.left=posX+offsetX;';
diff --git a/include/lib/icard.class.php b/include/lib/icard.class.php
index 9fbb74153..f1dc2367f 100644
--- a/include/lib/icard.class.php
+++ b/include/lib/icard.class.php
@@ -344,7 +344,7 @@ class ICard extends HtmlInput
     static public function test_me()
     {
         require_once NOALYSS_INCLUDE.'/lib/itext.class.php';
-        $_SESSION['isValid']=1;
+        $_SESSION[SESSION_KEY.'isValid']=1;
         $a=new ICard('testme');
         $a->extra="all";
         $a->set_attribute('label', 'ctl_label');
diff --git a/include/lib/idate.class.php b/include/lib/idate.class.php
index ea1a105d6..3deb069a9 100644
--- a/include/lib/idate.class.php
+++ b/include/lib/idate.class.php
@@ -18,16 +18,17 @@
  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-// Copyright Author Dany De Bontridder danydb@aevalys.eu
+// Copyright Author Dany De Bontridder danydb@noalyss.eu
 
   /**
    *\file
-   \brief Html Input
+   \brief Html Input Date type
   */
 
 
 /// Html Input : Input a date format dd.mm.yyyy
 /// The property title should be set to indicate what it is expected
+/// @see calendar-setup.js
 require_once NOALYSS_INCLUDE.'/lib/html_input.class.php';
 
 class IDate extends HtmlInput
@@ -74,14 +75,15 @@ class IDate extends HtmlInput
                 </span>
                 ',$this->name,$this->id,$this->value,$this->placeholder,$this->title,$this->id
                 );
-        
+        // @see calendar-setup.js
         $r.=sprintf('<script type="text/javascript">
                 Calendar.setup({'.
-                'inputField     :    "%s",     // id of the input field
-            ifFormat       :    "%%d.%%m.%%Y",      // format of the input field
-            button         :    "%s_trigger",  // trigger for the calendar (button ID)
-            align          :    "Bl",           // alignment (defaults to "Bl")
-            singleClick    :    true
+                'inputField     :    "%s",    
+            ifFormat       :    "%%d.%%m.%%Y",     
+            button         :    "%s_trigger",  
+            align          :    "Bl",         
+            singleClick    :    true,
+            firstDay:0 
         });
             </script>'
                 ,$this->id,$this->id);
diff --git a/include/lib/noalyss_csv.class.php b/include/lib/noalyss_csv.class.php
index 669403431..7e5675782 100644
--- a/include/lib/noalyss_csv.class.php
+++ b/include/lib/noalyss_csv.class.php
@@ -46,10 +46,10 @@ class Noalyss_Csv
         $this->size=0;
      
         $a_field=[';',','];
-        $this->sep_field=$a_field[$_SESSION['csv_fieldsep']];
+        $this->sep_field=$a_field[$_SESSION[SESSION_KEY.'csv_fieldsep']];
         $a_field=['.',','];
-        $this->sep_dec=$a_field[$_SESSION['csv_decimal']];
-        $this->encoding=$_SESSION['csv_encoding'];
+        $this->sep_dec=$a_field[$_SESSION[SESSION_KEY.'csv_decimal']];
+        $this->encoding=$_SESSION[SESSION_KEY.'csv_encoding'];
     
     }
 
diff --git a/include/lib/user_common.php b/include/lib/user_common.php
index 5c77c616c..5a2be362a 100644
--- a/include/lib/user_common.php
+++ b/include/lib/user_common.php
@@ -69,7 +69,7 @@ function isValid_deprecrated ($p_cn,$p_grpt_id)
  * \param $p_javascript javascript code to add
  * \note example :
 \verbatim
-   $step=$_SESSION['g_pagesize'];
+   $step=$_SESSION[SESSION_KEY.'g_pagesize'];
    $page=(isset($_GET['offset']))?$_GET['page']:1;
    $offset=(isset($_GET['offset']))?$_GET['offset']:0;
 
@@ -82,10 +82,10 @@ function navigation_bar($p_offset,$p_line,$p_size=0,$p_page=1,$p_javascript="")
 {
     // if the pagesize is unlimited return ""
     // in that case there is no nav. bar
-    if ( $_SESSION['g_pagesize'] == -1  ) return "";
+    if ( $_SESSION[SESSION_KEY.'g_pagesize'] == -1  ) return "";
     if ( $p_size==0)
     {
-        $p_size= $_SESSION['g_pagesize'];
+        $p_size= $_SESSION[SESSION_KEY.'g_pagesize'];
     }
     // if there is no row return an empty string
     if ( $p_line == 0 ) return "";
diff --git a/include/template/module.php b/include/template/module.php
index 2f792438b..09e635b23 100644
--- a/include/template/module.php
+++ b/include/template/module.php
@@ -11,14 +11,14 @@
 <?php
 $http=new HttpInput();
 if ( $cn->get_value("select count(*) from profile join profile_user using (p_id)
-		where user_name=$1 and with_calc=true",array($_SESSION['g_user'])) ==1):
+		where user_name=$1 and with_calc=true",array($_SESSION[SESSION_KEY.'g_user'])) ==1):
   echo '<div id="calc">';
 	echo IButton::show_calc();
 echo '</div>';
 endif;
 
 if ( $cn->get_value("select count(*) from profile join profile_user using (p_id)
-		where user_name=$1 and with_direct_form=true",array($_SESSION['g_user'])) ==1):
+		where user_name=$1 and with_direct_form=true",array($_SESSION[SESSION_KEY.'g_user'])) ==1):
 ?>
 	<div id="direct">
 	<form method="get">
diff --git a/include/template/todo_list_display.php b/include/template/todo_list_display.php
index ea4844ef9..3171c183b 100644
--- a/include/template/todo_list_display.php
+++ b/include/template/todo_list_display.php
@@ -100,7 +100,7 @@ echo HtmlInput::title_box("Note","todo_list_div".$this->tl_id,'close',$close_sha
     <?php echo HtmlInput::hidden('id',$this->tl_id) ?>
     <p style='text-align: center'>
         <ol style="list-style: none;">
-    <?php if ($this->use_login == $_SESSION['g_user']) : ?>
+    <?php if ($this->use_login == $_SESSION[SESSION_KEY.'g_user']) : ?>
             <li style="display:inline">
                 <input type="submit" class="smallbutton" value="<?php echo _('Sauve');?>" onclick="todo_list_save(<?php echo $this->tl_id?>);return false">
              </li>
diff --git a/unit-test/global.example.php b/unit-test/global.example.php
index 70f4ab106..69e2a515b 100644
--- a/unit-test/global.example.php
+++ b/unit-test/global.example.php
@@ -28,7 +28,7 @@ define ("DOSSIER",48);
 $_REQUEST['gDossier'] = DOSSIER;
 $g_connection=new Database(DOSSIER);
 $g_parameter = new Noalyss_Parameter_Folder($g_connection);
-$_SESSION['g_user']='phpcompta';
-$_SESSION['g_pass']='dany';
-$_SESSION['g_pagesize']='50';
+$_SESSION[SESSION_KEY.'g_user']='phpcompta';
+$_SESSION[SESSION_KEY.'g_pass']='dany';
+$_SESSION[SESSION_KEY.'g_pagesize']='50';
 $g_user=new User($g_connection);
diff --git a/unit-test/global.php b/unit-test/global.php
index e2271a2da..0d4a00530 100644
--- a/unit-test/global.php
+++ b/unit-test/global.php
@@ -29,9 +29,9 @@ if (!defined("DOSSIER"))define ("DOSSIER",25);
 $_REQUEST['gDossier'] = DOSSIER;
 $g_connection=new Database(DOSSIER);
 $g_parameter = new Noalyss_Parameter_Folder($g_connection);
-$_SESSION['g_user']='admin';
-$_SESSION['g_pass']='phpcompta';
-$_SESSION['g_pagesize']='50';
+$_SESSION[SESSION_KEY.'g_user']='admin';
+$_SESSION[SESSION_KEY.'g_pass']='phpcompta';
+$_SESSION[SESSION_KEY.'g_pagesize']='50';
 $g_user=new User($g_connection);
 
 require_once __DIR__.'/facility.class.php';
\ No newline at end of file