diff --git a/htdocs/core/class/hookmanager.class.php b/htdocs/core/class/hookmanager.class.php
index cca22038746..9154aaa2fdd 100755
--- a/htdocs/core/class/hookmanager.class.php
+++ b/htdocs/core/class/hookmanager.class.php
@@ -116,7 +116,7 @@ class HookManager
      * 	    @param		array	$parameters		Array of parameters
      * 		@param		Object	&$object		Object to use hooks on
      * 	    @param		string	&$action		Action code on calling page ('create', 'edit', 'view', 'add', 'update', 'delete'...)
-     * 		@return		mixed					For doActions,formObjectOptions:    Return 0 if we want to keep standard actions, >0 if if want to stop standard actions, <0 means KO.
+     * 		@return		mixed					For doActions,formObjectOptions,pdf_xxx:    								Return 0 if we want to keep standard actions, >0 if if want to stop standard actions, <0 means KO.
      * 											For printSearchForm,printLeftBlock,printTopRightMenu,formAddObjectLine,...: Return HTML string. TODO Must always return an int and things to print into ->resprints.
      *                                          Can also return some values into an array ->results.
      * 											$this->error or this->errors are also defined by class called by this function if error.
@@ -128,6 +128,11 @@ class HookManager
         $parameters['context']=join(':',$this->contextarray);
         dol_syslog(get_class($this).'::executeHooks method='.$method." action=".$action." context=".$parameters['context']);
 
+        // Define type of hook ('output', 'returnvalue' or 'addreplace')
+        $hooktype='output';
+        if (preg_match('/^pdf_/',$method)) $hooktype='returnvalue';	// pdf_xxx except pdf_writelinedesc are returnvalue hooks. When there is 2 hooks of this type, only last one win.
+        if ($method == 'doActions' || $method == 'formObjectOptions' || $method == 'pdf_writelinedesc') $hooktype='addreplace';
+
         // Loop on each hook to qualify modules that declared context
         $modulealreadyexecuted=array();
         $resaction=0; $error=0;
@@ -145,15 +150,15 @@ class HookManager
                 	// test to avoid to run twice a hook, when a module implements several active contexts
                     if (in_array($module,$modulealreadyexecuted)) continue;
                     $modulealreadyexecuted[$module]=$module;
-
                     // Hooks that return int
-                    if (($method == 'doActions' || $method == 'formObjectOptions'))
+                    if ($hooktype == 'addreplace')
                     {
-                    	$resaction+=$actionclassinstance->$method($parameters, $object, $action, $this); // $object and $action can be changed by method ($object->id during creation for example or $action to go back to other action for example)
+                    	$resaction += $actionclassinstance->$method($parameters, $object, $action, $this); // $object and $action can be changed by method ($object->id during creation for example or $action to go back to other action for example)
                     	if ($resaction < 0 || ! empty($actionclassinstance->error) || (! empty($actionclassinstance->errors) && count($actionclassinstance->errors) > 0))
                     	{
                     		$error++;
                     		$this->error=$actionclassinstance->error; $this->errors=array_merge($this->errors, (array) $actionclassinstance->errors);
+
                     		// TODO remove this. Change must be inside the method if required
                     		if ($method == 'doActions')
                     		{
@@ -164,11 +169,11 @@ class HookManager
                     }
                     // Generic hooks that return a string (printSearchForm, printLeftBlock, printTopRightMenu, formAddObjectLine, formBuilddocOptions, ...)
                     else
-                    {
+					{
                     	// TODO. this should be done into the method by returning nothing
                     	if (is_array($parameters) && ! empty($parameters['special_code']) && $parameters['special_code'] > 3 && $parameters['special_code'] != $actionclassinstance->module_number) continue;
 
-                    	$result = $actionclassinstance->$method($parameters, $object, $action, $this);
+                    	$result = $actionclassinstance->$method($parameters, $object, $action, $this); // $object and $action can be changed by method ($object->id during creation for example or $action to go back to other action for example)
 
                     	if (is_array($actionclassinstance->results))  $this->resArray =array_merge($this->resArray, $actionclassinstance->results);
                     	if (! empty($actionclassinstance->resprints)) $this->resPrint.=$actionclassinstance->resprints;
@@ -184,7 +189,9 @@ class HookManager
             }
         }
 
-        if ($method != 'doActions' && $method != 'formObjectOptions') return $this->resPrint;	// TODO remove this. When there is something to print, ->resPrint is filled.
+        // TODO remove this. When there is something to print for an output hook, ->resPrint is filled.
+        if ($hooktype == 'output') return $this->resPrint;
+		if ($hooktype == 'returnvalue') return $result;
         return ($error?-1:$resaction);
 	}
 
diff --git a/htdocs/core/lib/pdf.lib.php b/htdocs/core/lib/pdf.lib.php
index 8adbb1f9afc..ddd38a8484d 100644
--- a/htdocs/core/lib/pdf.lib.php
+++ b/htdocs/core/lib/pdf.lib.php
@@ -839,6 +839,7 @@ function pdf_writelinedesc(&$pdf,$object,$i,$outputlangs,$w,$h,$posx,$posy,$hide
 {
 	global $db, $conf, $langs, $hookmanager;
 
+	$reshook=0;
 	if (is_object($hookmanager) && ( ($object->lines[$i]->product_type == 9 && ! empty($object->lines[$i]->special_code) ) || ! empty($object->lines[$i]->fk_parent_line) ) )
 	{
 		$special_code = $object->lines[$i]->special_code;
@@ -847,7 +848,7 @@ function pdf_writelinedesc(&$pdf,$object,$i,$outputlangs,$w,$h,$posx,$posy,$hide
 		$action='';
 		$reshook=$hookmanager->executeHooks('pdf_writelinedesc',$parameters,$object,$action);    // Note that $action and $object may have been modified by some hooks
 	}
-	else
+	if (empty($reshook))
 	{
 		$labelproductservice=pdf_getlinedesc($object,$i,$outputlangs,$hideref,$hidedesc,$issupplierline);
 		// Description