Off Line Power Supply -- 1) A power supply in which the ac line voltage is rectified and filtered without using a line frequency isolation transformer. 2) A power supply switched into service upon line loss to provide power to the load without significant interruption. Also called Off Line Switchers (OLS).
Soft start: Sometimes the equipment that you are powering from the power supply has so much inrush current that it will shut down the power supply, or blow a fuse, or cause other damage. In this case you want to use a power supply that has a soft start to gradually increase the output voltage to keep the "out rush" current within a reasonable range.