(under the class definition) Subject matter having a siding in which the main-track switch is mechanically connected to a derailing-block or safety-switch in the siding, the derailing-block or safety-switch being opened when the main-track switch is closed, so that cars on the siding are prevented from fouling the main line.
(1) Note. For structure of the derailing block, a search should be made in subclass 163 of this class, and Class 104, Railways, subclasses 262+.
