=== modified file 'l10n_it_account/account/invoice.py'
--- l10n_it_account/account/invoice.py	2011-11-23 16:40:59 +0000
+++ l10n_it_account/account/invoice.py	2012-01-30 18:20:20 +0000
@@ -30,6 +30,14 @@
     
     _inherit = 'account.invoice'
 
+    _columns = {
+        'payment_term': fields.many2one('account.payment.term', 'Payment Term', readonly=True, states={'draft':[('readonly',False)]}, required=True,
+            help="If you use payment terms, the due date will be computed automatically at the generation "\
+                "of accounting entries. If you keep the payment term and the due date empty, it means direct payment. "\
+                "The payment term may compute several due dates, for example 50% now, 50% in one month."),
+        
+    }
+
     def action_number(self, cr, uid, ids, context=None):
         super(account_invoice, self).action_number(cr, uid, ids, context)
         for obj_inv in self.browse(cr, uid, ids):