In patch bay jargon this refers to a normal that is only broken by inserting a plug into one of two plugs that are normalled together. In typical patch bay design the top jack of any pair is usually not affected by having a plug inserted into it. It will still route signal down to its lower counterpart. When a jack is inserted into the lower plug, however, the normal connection is broken. This provides a convenient way to route signals to multiple destinations. For example, the output of a mixer that is normalled to the input of a DAT on the patch bay can also be simultaneously routed to another patch point. To do this one would simply run a patch cable from the patch point that is the output of the mixer (an upper jack) to the patch point that is the input to the other device (a lower jack). This connection will break the normal of what would normally be feeding that other device in favor of the mixer signal that has been patched in. Signal will now be routed to the DAT and the other device.