diff --git a/htdocs/core/ajax/fileupload.php b/htdocs/core/ajax/fileupload.php
index bd3d2b32ef5..5d4390bc04c 100644
--- a/htdocs/core/ajax/fileupload.php
+++ b/htdocs/core/ajax/fileupload.php
@@ -53,9 +53,9 @@ $element = GETPOST('element');
  */
 class UploadHandler
 {
-    private $options;
-    private $fk_elment;
-    private $element;
+    private $_options;
+    private $_fk_element;
+    private $_element;
 
 
     /**
@@ -70,10 +70,10 @@ class UploadHandler
 
     	global $conf;
 
-    	$this->fk_element=$fk_element;
-    	$this->element=$element;
+    	$this->_fk_element=$fk_element;
+    	$this->_element=$element;
 
-        $this->options = array(
+        $this->_options = array(
             'script_url' => $_SERVER['PHP_SELF'],
             'upload_dir' => $conf->$element->dir_output . '/' . $fk_element . '/',
             'upload_url' => DOL_URL_ROOT.'/document.php?modulepart='.$element.'&attachment=1&file=/'.$fk_element.'/',
@@ -102,7 +102,7 @@ class UploadHandler
             )
         );
         if ($options) {
-            $this->options = array_merge_recursive($this->options, $options);
+            $this->_options = array_merge_recursive($this->_options, $options);
         }
     }
 
@@ -114,22 +114,22 @@ class UploadHandler
      */
     private function get_file_object($file_name)
     {
-        $file_path = $this->options['upload_dir'].$file_name;
+        $file_path = $this->_options['upload_dir'].$file_name;
         if (is_file($file_path) && $file_name[0] !== '.')
         {
             $file = new stdClass();
             $file->name = $file_name;
             $file->mime = dol_mimetype($file_name,'',2);
             $file->size = filesize($file_path);
-            $file->url = $this->options['upload_url'].rawurlencode($file->name);
-            foreach($this->options['image_versions'] as $version => $options) {
+            $file->url = $this->_options['upload_url'].rawurlencode($file->name);
+            foreach($this->_options['image_versions'] as $version => $options) {
                 if (is_file($options['upload_dir'].$file_name)) {
                     $tmp=explode('.',$file->name);
                     $file->{$version.'_url'} = $options['upload_url'].rawurlencode($tmp[0].'_mini.'.$tmp[1]);
                 }
             }
-            $file->delete_url = $this->options['script_url']
-                .'?file='.rawurlencode($file->name).'&fk_element='.$this->fk_element.'&element='.$this->element;
+            $file->delete_url = $this->_options['script_url']
+                .'?file='.rawurlencode($file->name).'&fk_element='.$this->_fk_element.'&element='.$this->_element;
             $file->delete_type = 'DELETE';
             return $file;
         }
@@ -143,7 +143,7 @@ class UploadHandler
      */
     private function get_file_objects()
     {
-        return array_values(array_filter(array_map(array($this, 'get_file_object'), scandir($this->options['upload_dir']))));
+        return array_values(array_filter(array_map(array($this, 'get_file_object'), scandir($this->_options['upload_dir']))));
     }
 
     /**
@@ -156,7 +156,7 @@ class UploadHandler
     private function create_scaled_image($file_name, $options)
     {
         global $maxwidthmini, $maxheightmini;
-        $file_path = $this->options['upload_dir'].$file_name;
+        $file_path = $this->_options['upload_dir'].$file_name;
         $new_file_path = $options['upload_dir'].$file_name;
 
         if (create_exdir($options['upload_dir']) >= 0)
@@ -191,7 +191,7 @@ class UploadHandler
         if ($error) {
             return $error;
         }
-        if (!preg_match($this->options['accept_file_types'], $file->name)) {
+        if (!preg_match($this->_options['accept_file_types'], $file->name)) {
             return 'acceptFileTypes';
         }
         if ($uploaded_file && is_uploaded_file($uploaded_file)) {
@@ -199,18 +199,18 @@ class UploadHandler
         } else {
             $file_size = $_SERVER['CONTENT_LENGTH'];
         }
-        if ($this->options['max_file_size'] && (
-                $file_size > $this->options['max_file_size'] ||
-                $file->size > $this->options['max_file_size'])
+        if ($this->_options['max_file_size'] && (
+                $file_size > $this->_options['max_file_size'] ||
+                $file->size > $this->_options['max_file_size'])
             ) {
             return 'maxFileSize';
         }
-        if ($this->options['min_file_size'] &&
-            $file_size < $this->options['min_file_size']) {
+        if ($this->_options['min_file_size'] &&
+            $file_size < $this->_options['min_file_size']) {
             return 'minFileSize';
         }
-        if (is_int($this->options['max_number_of_files']) && (
-                count($this->get_file_objects()) >= $this->options['max_number_of_files'])
+        if (is_int($this->_options['max_number_of_files']) && (
+                count($this->get_file_objects()) >= $this->_options['max_number_of_files'])
             ) {
             return 'maxNumberOfFiles';
         }
@@ -235,11 +235,11 @@ class UploadHandler
         $file->size = intval($size);
         $file->type = $type;
         $error = $this->has_error($uploaded_file, $file, $error);
-        if (!$error && $file->name && create_exdir($this->options['upload_dir']) >= 0) {
+        if (!$error && $file->name && create_exdir($this->_options['upload_dir']) >= 0) {
             if ($file->name[0] === '.') {
                 $file->name = substr($file->name, 1);
             }
-            $file_path = $this->options['upload_dir'].$file->name;
+            $file_path = $this->_options['upload_dir'].$file->name;
             $append_file = is_file($file_path) && $file->size > filesize($file_path);
             clearstatcache();
             if ($uploaded_file && is_uploaded_file($uploaded_file)) {
@@ -264,8 +264,8 @@ class UploadHandler
             }
             $file_size = filesize($file_path);
             if ($file_size === $file->size) {
-                $file->url = $this->options['upload_url'].rawurlencode($file->name);
-                foreach($this->options['image_versions'] as $version => $options)
+                $file->url = $this->_options['upload_url'].rawurlencode($file->name);
+                foreach($this->_options['image_versions'] as $version => $options)
                 {
                     if ($this->create_scaled_image($file->name, $options))
                     {
@@ -273,13 +273,13 @@ class UploadHandler
                         $file->{$version.'_url'} = $options['upload_url'].rawurlencode($tmp[0].'_mini.'.$tmp[1]);
                     }
                 }
-            } else if ($this->options['discard_aborted_uploads']) {
+            } else if ($this->_options['discard_aborted_uploads']) {
                 unlink($file_path);
                 $file->error = 'abort';
             }
             $file->size = $file_size;
-            $file->delete_url = $this->options['script_url']
-                .'?file='.rawurlencode($file->name).'&fk_element='.$this->fk_element.'&element='.$this->element;
+            $file->delete_url = $this->_options['script_url']
+                .'?file='.rawurlencode($file->name).'&fk_element='.$this->_fk_element.'&element='.$this->_element;
             $file->delete_type = 'DELETE';
         } else {
             $file->error = $error;
@@ -312,8 +312,8 @@ class UploadHandler
      */
     public function post()
     {
-        $upload = isset($_FILES[$this->options['param_name']]) ?
-            $_FILES[$this->options['param_name']] : array(
+        $upload = isset($_FILES[$this->_options['param_name']]) ?
+            $_FILES[$this->_options['param_name']] : array(
                 'tmp_name' => null,
                 'name' => null,
                 'size' => null,
@@ -359,10 +359,10 @@ class UploadHandler
     {
         $file_name = isset($_REQUEST['file']) ?
             basename(stripslashes($_REQUEST['file'])) : null;
-        $file_path = $this->options['upload_dir'].$file_name;
+        $file_path = $this->_options['upload_dir'].$file_name;
         $success = is_file($file_path) && $file_name[0] !== '.' && unlink($file_path);
         if ($success) {
-            foreach($this->options['image_versions'] as $version => $options) {
+            foreach($this->_options['image_versions'] as $version => $options) {
                 $file = $options['upload_dir'].$file_name;
                 if (is_file($file)) {
                     unlink($file);