I would guess that the GP means designing such that your board accepts multiple footprints for compatible parts, so that if your first choice of op amp (or volt

I would guess that the GP means designing such that your board accepts multiple footprints for compatible parts, so that if your first choice of op amp (or voltage regulator, etc) goes out of stock you can populate another one. That might be a similar part by another company, or it might be an identical part in a different package (often ICs are available in two or three package shapes, and you might not be able to predict which ones will be in stock).