What is the definition of 'absolute signals' in train operations?

The definition of 'absolute signals' in train operations is accurately represented by the notion of signals that authorize the movement of trains without restriction. These signals are critical as they permit trains to proceed through a section of track with the assurance that it is safe to do so, thereby allowing them to continue their journey without any conditions attached.

This concept is fundamental to maintaining an organized and safe flow of train traffic. When an absolute signal is displayed, it signifies to the train crew that they can move forward, providing clarity and preventing potential confusion that could arise from ambiguous signals.

The other options describe different types of signals or functions that do not align with the definition of absolute signals. For example, signals allowing only passenger trains to proceed, those that inform about track conditions ahead, or those that indicate an immediate stop serve other operational purposes but do not provide the unrestricted movement authorization that characterizes absolute signals.