When master planning runs if there is a requirement then it will generate a planned purchase order if the item is setup for purchasing as the replenishment. When you firm planned orders to actual orders you might want to consider do you create one purchase order or multiple purchase orders if they are for the same supplier. There might be times where it makes sense to place one purchase order if you get a total order discount for example. There is a parameter in master planning called group by vendor which will enable you to setup a default if you want to consolidate. Just keep in mind this parameter can be changed by the person firming as you will see in the video which might be useful in circumstances where you most of the time group by on the special occasion you want to split up into a separate PO.
Here is a quick overview.
AX2012 R3 CU11.