Plan processes at their simplest, level 1, are point solutions. Plans are created internally, with no integrated processes between different functions or plants within the company. Basic tools spreadsheets and simple material requirements planning (MRP) or inventory control tools support the process.

At level 2, the planning processes pick up and aggregate demand across the firm. Simple MRP planning tools are augmented with finite capacity planning capability S&OP and later advanced planning and scheduling systems which allows the firm to create reliable plans that can be adapted to ensure that more focused performance goals can be met. The planning now takes place across functional boundaries, so the firm moves toward internal supply chain excellence.

Between level 2 and level 3 is the wall between my company and your company. This wall acts as a psychological barrier to improvement, but the more innovative firms break through, extending their processes into their suppliers and customers. Now they can pick up advanced demand forecasts from customers and give their suppliers early warning of changes in market conditions and cancelation or reduction of supply rates. This condition increasingly takes place collaboratively, with direct, electronic interchange of data between planning systems, governed by strict rules of engagement, such as service level agreements between collaborating partners in the extended value chain.

Level 4 planning takes in more steps in the extended chain. Some firms can travel back four or five levels in the chains supplying key components.