Great find @LarsonSolutions! Planning BOM was introduced for K2022.1, and I’ve never understood it (or found a use case for it)… but the Release Guide describes it thusly:
“Planning Bill of Material is an unbuildable BOM that allows the user to express the lower-level parts as a percentage of the total number to be sold. This is the traditional way for manufacturers to forecast lower level parts. A typical use-case entails a non-sellable, non-buildable part at the top with a quantity to build for a period of time. Each of the components of the BOM have a quantity per, and a percentage. If the user has options, then each option is represented along with the quantity per and percentage. As the parts are consumed by actual sales orders, the forecast quantities are consumed. Once the Planning BOM is active, MRP will see it as forecasted.”
I was first introduced to planning BOMs in APICS training, er, a while ago. The idea was to explode a forecast into some desired mix. It makes it easy to change the total forecast or just the mix all in one.