一段来自Wikipedia的关于MRP的解释：

Material Requirements Planning (MRP) is a software based production planning and inventory control system used to manage manufacturing processes. Although it is not common nowadays, it is possible to conduct MRP by hand as well.

An MRP system is intended to simultaneously meet three objectives:

• Ensure materials and products are available for production and delivery to customers.  -- 确保足够的原材料和产品可供生产以及交付给客户
• Maintain the lowest possible level of inventory.  -- 尽可能保持最低水平的库存
• Plan manufacturing activities, delivery schedules and purchasing activities. -- 计划制造活动，交货时间表和采购活动

Reference: http://en.wikipedia.org/wiki/Material_requirements_planning