Normalization
It is conventional to have the top row of jacks wired at the rear to outputs and bottom row of jacks wired to inputs. Patch bays may be half-normal (usually bottom) or full-normal, "normal" indicating that the top and bottom jacks are connected internally. When a patch bay has half-normal wiring, then with no patch cord inserted into either jack, the top jack is internally linked to the bottom jack via break contacts on the bottom jack; inserting a patch cord into the top jack will take a feed off that jack while retaining the internal link between the two jacks; inserting a patch cord into the bottom jack will break the internal link and replace the signal feed from the top jack with the signal carried on the patch cord. If a patch bay is wired to full-normal, then it includes break contacts in both rows of jacks.
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