refug = fields.Function(
                    fields.Char(
                        string = u'Référence UG',
                        help=u'Référence UG',
                        states=STATES,
                        depends=DEPENDS
                    ),
            '_get_refug',
            searcher='search_refug'
        )

    def _get_refug(self, ids):
        u'Référence UG'
        if self.code is None:
            return None
        else:
            return '%s %s' % (self.equipement.coder, self.code)

    @classmethod
    def search_refug(cls, name, clause):
        return [('equipement.coder',) + tuple(clause[1:])]