1) That point in time inside of which the forecast is no longer included in total demand and projected available inventory calculations; inside this point only customer orders are considered. Beyond this point, total demand is a combination of actual orders and forecasts, depending on the forecast consumption technique chosen. 2) In some contexts, the demand time fence may correspond to that point in the future inside which changes to the master schedule must be approved by an authority higher than the master scheduler. Note, however, that customer orders may still be promised inside the demand time。fence without higher authority approval if there are quantities available-to-promise (ATP). Beyond the demand time fence, the master scheduler may change the MPS within the limits of established rescheduling rules without the approval of higher authority. See: option over planning, planning time fence, time fence.   需求时界—1）总需求和预计可用库存计算之中不再包含预测的时间点；在该时间点内，只考虑客户订单。在该时间点外，总需求为实际订单和预测的综合，取决于预测冲减技术的选择。 2）在某些情况下，需求时界对应于未来的一个时间点。该时间点内，主计划的变动必须征得主计划员上一层负责人的批准。然而必须注意，如果有大量的可承诺量（ATP），则顾客订单仍可在需求时界内进行承诺，而不需要高层批准。需求时界之外，主计划员可在已建立的重排程规划规则限制下变动MPS,无需高级负责人批准。参见：option overplanning,planning time fence,time fence.