Every module in this book reaches into one shared drawer: the product catalogue. Sales sells from it, Procurement buys into it, Inventory shelves it, Manufacturing builds with it, and the prices and costs in this chapter decide what every one of those documents is worth. A product here is anything your company buys, sells, makes, stocks, or charges for — a bag of feed, a finished table, an hour of consultancy.
This chapter is about the catalogue itself: the product record and everything on it, the units quantities are counted in, the prices your documents will charge and pay, the costs your margins are measured against, and the bills of materials that say what a made thing is made of. Get this chapter right and the others get easier: most "the system priced it wrong" stories are, on inspection, catalogue stories — a unit misunderstood, a price row too broad, a cost nobody maintained.