Special Markings:
A-b, a-c, aft escape hatch, b-c, bridge hatch, screws mess hatch, engine room control, exhaust valve shut, forward escape hatch, hatches and vents fully opened-lighted intermediate-lighted fully shut-lighted, hull ind, hull openings, hull openings fully opened-lighted, fully shut-lighted, hull ind, hull openings, hull openings fully opened-lighted intermediate-no light fully shut-lighted, main ind/shown twice/main snorkel exhaust/shown twice/muffler exhaust aft engines forward engines, negative vent, off, open/shown three times/phase selector switch for hyd, valve control for vent and flood valves, power on, snorkel exhaust aft engines forward engines, torpedo load hatch