An assembly of hardware so arranged that a number of circuits, usually of the same or similar type, appear on jacks for monitoring, interconnecting, and testing purposes. Note 1: Patch bays are used at many locations, such as technical control facilities, patch and test facilities, and at telephone exchanges. Note 2: Patch bays facilitate flexibility in the use, routing or restoration of a variety of circuit types, such as dc, VF, group, coaxial, equal-level, and digital data circuits.