Thermal management for improved energy efficiency and reliability of electronic equipment is applicable during the design phase at the device, printed board assembly (PBA), shelf and system level. This document currently addresses requirements from the PBA level and above. It applies to stand alone circuit packs as well as to fully populated shelves, cabinets and other enclosures employing either natural convection or forced-air cooling. It does not currently apply to the internal thermal design of a packaged component, e.g., a packaged semiconductor device.