@staticmethod
def p_characteristic_optional(p):
    """characteristic_optional : display_identifier
                                   | format
                                   | byte_order
                                   | bit_mask
                                   | function_list
                                   | number
                                   | extended_limits
                                   | read_only
                                   | guard_rails
                                   | map_list
                                   | max_refresh
                                   | dependent_characteristic
                                   | virtual_characteristic
                                   | ref_memory_segment
                                   | annotation
                                   | comparison_quantity
                                   | if_data_characteristic
                                   | axis_descr
                                   | calibration_access
                                   | matrix_dim
                                   | ecu_address_extension"""
    p[0] = p.slice[1].type, p[1]
