diff --git a/src/lib/Category.php b/src/lib/Category.php
index 46ad77c..37d4d85 100644
--- a/src/lib/Category.php
+++ b/src/lib/Category.php
@@ -7,32 +7,38 @@ use Garradin\DB;
 class Category
 {
   public function add($data = [])
+  // add new category
 	{
 		DB::getInstance()->insert('plugin_materiels_category', $data);
 	}
 
   public function edit($id, $data = [])
+  // edit a specific category
 	{
     $db = DB::getInstance();
     $db->update('plugin_materiels_category', $data, $db->where('id', $id));
 	}
 
   public function delete($id)
+  // delete a specific category
 	{
 		DB::getInstance()->delete('plugin_materiels_category', 'id = ' . $id);
 	}
 
   public function get($id)
+  // get and return a specific category
   {
     return DB::getInstance()->first('SELECT * FROM plugin_materiels_category WHERE id = ?;', $id);
   }
 
   public function listAll()
+  // return a list of all categories ordered by name
 	{
 		return DB::getInstance()->get('SELECT * FROM plugin_materiels_category ORDER BY name;');
 	}
 
   public function listAllEquipments($id)
+  // return a list of all equipments for a specific category ordered by equipments's designation
   {
     return DB::getInstance()->get(
         'SELECT * FROM plugin_materiels_equipment WHERE category_id = ? ORDER BY designation;', $id);
diff --git a/src/lib/Equipment.php b/src/lib/Equipment.php
index f0e8368..f113477 100644
--- a/src/lib/Equipment.php
+++ b/src/lib/Equipment.php
@@ -41,7 +41,8 @@ class Equipment
     return $eqmts_by_cat;
   }
 
-  public function CalculateStock($id)
+  public function CalculateOwned($id)
+  // return number of equipments owned
   {
     $entries = DB::getInstance()->firstColumn(
       "SELECT sum(equipment_number) FROM plugin_materiels_entry WHERE kind IN (
@@ -52,7 +53,8 @@ class Equipment
     return $entries - $outputs;
   }
 
-  public function CalculateOutOfStock($id)
+  public function CalculateOwnedOut($id)
+  // return number of equipments owned out
   {
     $entries = DB::getInstance()->firstColumn(
       "SELECT sum(equipment_number) FROM plugin_materiels_entry WHERE kind = 'Retour de location / prêt' AND equipment_id = ?;", $id);
@@ -62,6 +64,7 @@ class Equipment
   }
 
   public function CalculateNoOwned($id)
+  // return number of equipments no owned
   {
     $entries = DB::getInstance()->firstColumn(
       "SELECT sum(equipment_number) FROM plugin_materiels_entry WHERE kind = 'Location / Prêt' AND equipment_id = ?;", $id);
@@ -71,28 +74,33 @@ class Equipment
   }
 
   public function AllListsAll($eqmts)
+  // construct and return 3 lists with a specific list of equipments:
+  // equipments owned, equipments no owned and equipments just listed
   {
     $eqmts_owned = array();
     $eqmts_no_owned = array();
     $eqmts_just_listed = array();
     foreach ($eqmts as $eqmt) {
-      $stock = $this->CalculateStock($eqmt->id);
-      if ($stock) {
-        $eqmt->stock = $stock;
-        $out_of_stock = $this->CalculateOutOfStock($eqmt->id);
-        if ($out_of_stock) {
-          $eqmt->out_of_stock = $out_of_stock;
+      $owned = $this->CalculateOwned($eqmt->id);
+      if ($owned) {
+        // add equipment to list of equiments owned with his number and number of out
+        $eqmt->owned = $owned;
+        $owned_out = $this->CalculateOwnedOut($eqmt->id);
+        if ($owned_out) {
+          $eqmt->owned_out = $owned_out;
         } else {
-          $eqmt->out_of_stock = 0;
+          $eqmt->owned_out = 0;
         }
         array_push($eqmts_owned, $eqmt);
       }
       $no_owned = $this->CalculateNoOwned($eqmt->id);
       if ($no_owned) {
+        // add equipment to list of equiments no owned with his number
         $eqmt->no_owned = $no_owned;
         array_push($eqmts_no_owned, $eqmt);
       }
-      if ($stock + $no_owned == 0) {
+      if ($owned + $no_owned == 0) {
+        // add equipment to list of equiments just listed
         array_push($eqmts_just_listed, $eqmt);
       }
     }
@@ -172,7 +180,7 @@ class Equipment
     foreach ($eqmts_by_cat as $cat => $eqmts) {
       $eqmts_released = array();
       foreach ($eqmts as $eqmt) {
-        $released = $this->CalculateOutOfStock($eqmt->id);
+        $released = $this->CalculateOwnedOut($eqmt->id);
         if ($released) {
           $eqmt->released = $released;
           array_push($eqmts_released, $eqmt);
diff --git a/src/templates/categories/materiels_par_categorie.tpl b/src/templates/categories/materiels_par_categorie.tpl
index 2051f97..e2eae6c 100644
--- a/src/templates/categories/materiels_par_categorie.tpl
+++ b/src/templates/categories/materiels_par_categorie.tpl
@@ -23,9 +23,9 @@
       {foreach from=$eqmts_owned item="eqmt"}
         <tr>
           <td>{$eqmt.designation}</td>
-          <td style="text-align: center;">{$eqmt.stock}</td>
-          <td style="text-align: center;">{$eqmt.out_of_stock}</td>
-          <td style="text-align: center;">{$eqmt.stock - $eqmt.out_of_stock}</td>
+          <td style="text-align: center;">{$eqmt.owned}</td>
+          <td style="text-align: center;">{$eqmt.owned_out}</td>
+          <td style="text-align: center;">{$eqmt.owned - $eqmt.owned_out}</td>
         </tr>
       {/foreach}
     </tbody>
diff --git a/src/templates/index.tpl b/src/templates/index.tpl
index b2234da..9ed0d5d 100644
--- a/src/templates/index.tpl
+++ b/src/templates/index.tpl
@@ -23,9 +23,9 @@
 				{foreach from=$eqmts item="eqmt"}
 					<tr>
 						<td>{$eqmt.designation}</td>
-						<td style="text-align: center;">{$eqmt.stock}</td>
-						<td style="text-align: center;">{$eqmt.out_of_stock}</td>
-						<td style="text-align: center;">{$eqmt.stock - $eqmt.out_of_stock}</td>
+						<td style="text-align: center;">{$eqmt.owned}</td>
+						<td style="text-align: center;">{$eqmt.owned_out}</td>
+						<td style="text-align: center;">{$eqmt.owned - $eqmt.owned_out}</td>
 						<td class="actions" style="text-align: center;">
 							{linkbutton shape="edit" label="Historique des entrées / sorties" href="historique.php?id=%d"|args:$eqmt.id}
           		{linkbutton shape="edit" label="Modifier" href="modifier_materiel.php?id=%d"|args:$eqmt.id}