Slang for Power Distribution Device, or PD. May provide 120 or 208V power and over-current protection for moving lights, audio racks, AV equipment, chain hoists, etc., and output via Socapex, L6-20, L21-30, NEMA 5-15 (Edison) outlets. Photo courtesy Motion Labs. In the US, portable power distribution equipment should be built and listed to the UL1640 standard. See also http://www.controlbooth.com/forums/lighting/14550-rack-mounted-voltage-meters.html.