Thanks. Usually, by attaching the negative terminal, for example, to this terminal, the output is then positive referenced to earth ground, and vice versa for connecting the positive terminal. Otherwise, it is floating. I am new to this, and I wanted to know if there were other uses. I appreciate the help.
One caution! If you power a circuit with mixed signals or a circuit that has both analog and digital grounds I would not reference the power supplies to ground. If you do this simply ties the two grounds together. Not a good idea, analog signals tend to be noisy and tying grounds will just give non-predictable results on the digital side.