Hello 
I want to display on front end « mpn » I saw topic :
<?php echo $this->product->product_mpn ?> 
But Where we have to add this code please ? Which file ?
Also I want to translate it what is the name constant ?
Thank you 
Regards 
			
			
			
				The exact code is different for product & category pages:
$this->product      is for productdetails page
$product->   is for product fields on the category page
It should go into your template overrides, which one(s) and where depends on the above and where you want to display the mpn.
No translation is required.
			
			
			
				Hello thank you for your answer.
It is on the product details page under the name of the product example under the title « cercle à tarte ... »
https://www.perledoree.fr/moule-patisserie/moule-de-cuisson/cercle-à-tarte-perforé-ø-28cm-detail.html
Thank you 
			
			
			
				OK so I have no idea how that template is built, but in standard VM the product title code is in the productdetails default.php
So assuming the template follows standard VM layout the override template file to edit is 
templates/theme684/html/com_virtuemart/productdetails/default.php
In the VM default template the title H1 is labelled <?php // Product Title   ?>
You should be able to work it out from there. You may want to add a css class to your code to style the output.
			
			
			
				Ok it is solved thank you