--- product-old.py	2013-09-09 16:11:02.000000000 -0700
+++ product.py	2014-02-21 16:07:02.000000000 -0800
@@ -32,12 +32,15 @@
 
 def ean_checksum(eancode):
     """returns the checksum of an ean string of length 13, returns -1 if the string has the wrong length"""
-    if len(eancode) <> 13:
+    if len(eancode) < 12 or len(eancode) > 13:
         return -1
     oddsum=0
     evensum=0
     total=0
-    eanvalue=eancode
+    if len(eancode) == 13:
+        eanvalue = eancode
+    else:
+        eanvalue = '0'+eancode
     reversevalue = eanvalue[::-1]
     finalean=reversevalue[1:]
 
@@ -55,7 +58,7 @@
     """returns True if eancode is a valid ean13 string, or null"""
     if not eancode:
         return True
-    if len(eancode) <> 13:
+    if len(eancode) < 12 or len(eancode) > 13:
         return False
     try:
         int(eancode)
@@ -554,7 +557,7 @@
         'active': fields.boolean('Active', help="If unchecked, it will allow you to hide the product without removing it."),
         'variants': fields.char('Variants', size=64),
         'product_tmpl_id': fields.many2one('product.template', 'Product Template', required=True, ondelete="cascade", select=True),
-        'ean13': fields.char('EAN13 Barcode', size=13, help="International Article Number used for product identification."),
+        'ean13': fields.char('UPC-A/EAN13 Barcode', size=13, help="International Article Number used for product identification."),
         'packaging' : fields.one2many('product.packaging', 'product_id', 'Logistical Units', help="Gives the different ways to package the same product. This has no impact on the picking order and is mainly used if you use the EDI module."),
         'price_extra': fields.float('Variant Price Extra', digits_compute=dp.get_precision('Product Price')),
         'price_margin': fields.float('Variant Price Margin', digits_compute=dp.get_precision('Product Price')),
@@ -819,7 +822,11 @@
     def checksum(ean):
         salt = '31' * 6 + '3'
         sum = 0
-        for ean_part, salt_part in zip(ean, salt):
+        if len(ean) == 13:
+            eanc = ean
+        else:
+            eanc = '0'+ean
+        for ean_part, salt_part in zip(eanc, salt):
             sum += int(ean_part) * int(salt_part)
         return (10 - (sum % 10)) % 10
     checksum = staticmethod(checksum)