Note: All file paths (folders) are relative to either master.dat (or critter.dat) if packed, or to Fallout's/Fallout 2's DATA folder if unpacked. This document describes the format of Fallout and Fallout 2 .PRO (Prototype) files, which are located in PROTO/. Each item, critter, wall, tile, and piece of scenery in the game has its own corresponding PRO file. The PRO file name is usually generated using the object's ObjectID, pre-padded by zeros so that it's 8 digits. For example, ObjectID of 32 would become 00000032.PRO.