This is a read-create setting that defines the action applied to the 'C' signaling bit of the incoming ABCD pattern, following the same per-bit action model used for the A and B bits. An admin uses it to correct or remap the C-bit specifically when it carries a supervisory signal, such as a wink or flash, that needs translation between the connected equipment's convention and the module's expectation. For example, mismatched C-bit handling could cause a PBX to miss a disconnect supervision signal, which correcting this action would fix.