diff --git a/filter.php b/filter.php
index 10ff43a9eef553cd6a55b28ce89788b3c90b9586..95a8cb1b8c61b7ad0e8a63b50059a3b036f41594 100644
--- a/filter.php
+++ b/filter.php
@@ -124,6 +124,8 @@ public function filter_iena_add_delimiters($pieces)
  * @param $text
  * @param array $options
  * @return string
+ * 
+ * Transform code for links into code for pop-up buttons
  */
 function filter($text, array $options = array())
 {
@@ -131,7 +133,7 @@ function filter($text, array $options = array())
 	global $CFG;
 	global $PAGE;
 
-    // Récupérer le style pour appliquer le même
+    // Apply context style to buttons
 	if ($CFG->color_btn) {
 		$this->color_btn = $CFG->color_btn;
 	}
@@ -151,17 +153,22 @@ function filter($text, array $options = array())
 		}
 	}
 
+    /* Looks for link(s) in the argument text and place them in the array named
+    matches */
 	preg_match_all('/<a href="(.*?)">(.*?)<\/a>/s', $text, $matches);
 
+    // ? remove tags opening links in new tab from $text ?
 	for ($i = 0; $i < count($matches[0]); $i++) {
 		if (strcmp($matches[1][$i], $matches[2][$i]) == 0) {
 			$text = str_replace($matches[0][$i], $matches[1][$i], $text);
 		}
 	}
 
+    // ? add start and end tags around links in $text ?
 	$pieces = explode($CFG->wwwroot . '/mod', $text);
 	$pieces = $this->filter_iena_add_delimiters($pieces);
 
+    // 
 	for ($i = 0; $i < count($pieces); $i++) {
 		$pieces[$i] = ' ' . $pieces[$i];
 		$ini = strpos($pieces[$i], $this->start);