diff --git a/htdocs/core/class/commonobjectline.class.php b/htdocs/core/class/commonobjectline.class.php
index 5a09dbfed29..f04e2da11ee 100644
--- a/htdocs/core/class/commonobjectline.class.php
+++ b/htdocs/core/class/commonobjectline.class.php
@@ -54,8 +54,8 @@ abstract class CommonObjectLine extends CommonObject
 	 *	Returns the translation key from units dictionary.
 	 *  A langs->trans() must be called on result to get translated value.
 	 *
-	 * 	@param	string $type Label type (long or short)
-	 *	@return	string|int <0 if ko, label if ok
+	 * 	@param	string $type 	Label type (long or short). This can be a translation key.
+	 *	@return	string|int 		<0 if ko, label if ok
 	 */
 	public function getLabelOfUnit($type = 'long')
 	{