In OpenERP V6 new attribute is introduced with good functionality and usability that is called change_default. Example. 'zip': fields.char('Zip', change_default=True, size=24), By default value of change_default is False, If change_default=True then while setting default value on any field we can make that field dependent on value of the other field of the same object which has change_default=True. Here is the video to explain the functionality.