diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index c56bd1cdf29..6ebd5112ec4 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -477,12 +477,14 @@ abstract class CommonObject
 	public $fk_multicurrency;
 
 	/**
-	 * @var string		Multicurrency code
+	 * @var string|array<int,string>    Multicurrency code
+	 *                                  Or, just for the Paiement object, an array: invoice ID => currency code for that invoice.
 	 */
 	public $multicurrency_code;
 
 	/**
-	 * @var float		Multicurrency rate
+	 * @var float|array<int,float>      Multicurrency rate ("tx" = "taux" in French)
+	 *                                  Or, just for the Paiement object, an array: invoice ID => currency rate for that invoice.
 	 */
 	public $multicurrency_tx;