In PP,Firmed Planned Orders, What is its use in Production?

What is firmed planned orders and what is its use in production?
Under what circumstances should it be use. Is it applicable to MPS item alone?

Firming is applicable to all types of planned orders and not only MPS items.

It is used when you don't want certain planned orders to change during subsequent MRP runs.

Say today you have created certain palnned orders.

In a normal scenario, when you do the MRP run again, the planned order may get changed if the requirements have changed.

However as a normal business practice, it is not desired to change the production plans everytime there is a change in the requirement...especially in the immediate future (maybe a week or so).

We set this as the planning time fence depending on the MRP type settimg in the material master, you may have firm orders.

Apart from MPS items, MRP will also generate firm planned orders for materials with MRP type P1 to P4.

In addition to the above, any planned order that is manually changed is also firmed.