My experiences with "blue printing" involves the Cal-P (Pool 3). If another engineer ran around you while enroute to Roseville, which is to say he made a bona fide departure from Oakland after you did but arrived at the designated arrival point for Roseville before you did, then you "blue printed" him when when you signed the off in the register at the engine crew. You put a 1 next to your name and wrote his name in with a 2. That way if you were both rested and a train was called Roseville - Oakland, you went first. I don't recall Pools 1 (Tracy), 2 (City), or 4 (Watsonville) having this sort of provision, but they may have.