Normalisation is where some signal paths are already made internally. Especially implemented in the Roland System 100. The name comes from when a socket does not have a jack inserted it is in its normal position. There is often a connection between the signal lug of the socket and an extra contact called the NC (normally closed) lug. It is this third lug on the socket that is used for the normalisation. Inserting a jack plug will break the connection between the NC and the signal lug. Sometimes a bus is provided for connecting the NC lugs.