In telecommunication, linearity is the property of a system in which, if input signals X and Y result in system outputS (X ) and S (Y ) respectively, the input signalaX + bY will result in the output aS (X ) + bS (Y ), where S is the system transfer function and a and b are scalars.
... Cross tube station (for the Jubilee Line)
Holborn tube station (for the Aldwych branch of the Piccadilly Line)
These stations once served by the Metropolitan Line, ...