Which signal automatically displays the same aspect and helps define limits of interlocking?

The signal that automatically displays the same aspect and helps define the limits of interlocking is the home signal. Home signals serve as primary indicators of the status of the track ahead, providing critical information to train operators regarding whether it is safe to proceed or if they should prepare to stop. They mark the beginning of a block where interlocking movements can take place, ensuring that trains are only allowed to enter specific track sections when it is safe to do so.

Home signals generally indicate both the position of trains and the overall status of track sections within interlocking limits, fundamentally supporting the operation of the rail system by preventing collisions and ensuring efficient traffic flow. This is essential for maintaining safety and order in railway operations.

The other signals mentioned serve different purposes: approach signals inform operators about the upcoming status of the next signal, marker signals delineate the boundaries of special zones or interlocking areas but do not provide the same operational limits as home signals, and dwarf signals typically signal movements at lower speed and are often used for specific track conditions rather than interlocking limits.