diff --git a/htdocs/compta/facture/class/api_invoices.class.php b/htdocs/compta/facture/class/api_invoices.class.php
index c1f6b6fdd49..03b6abde947 100644
--- a/htdocs/compta/facture/class/api_invoices.class.php
+++ b/htdocs/compta/facture/class/api_invoices.class.php
@@ -277,7 +277,7 @@ class Invoices extends DolibarrApi
     }
 
     /**
-     * Get lines of an invoice
+     * Get lines of a given invoice
      *
      * @param int   $id             Id of invoice
      *
@@ -307,7 +307,9 @@ class Invoices extends DolibarrApi
     }
     
     /**
-     * Add a line to given invoice
+     * Add a line to a given invoice
+     * 
+     * Exemple of POST query : { "desc": "Desc", "subprice": "1.00000000", "qty": "1", "tva_tx": "20.000", "localtax1_tx": "0.000", "localtax2_tx": "0.000", "fk_product": "1", "remise_percent": "0", "date_start": "", "date_end": "", "fk_code_ventilation": 0,  "info_bits": "0", "fk_remise_except": null,  "product_type": "1", "rang": "-1", "special_code": "0", "fk_parent_line": null, "fk_fournprice": null, "pa_ht": "0.00000000", "label": "", "array_options": [], "situation_percent": "100", "fk_prev_id": null, "fk_unit": null }   
      *
      * @param int   $id             Id of invoice
      * @param array $request_data   Invoiceline data