What is indicated by the key on "W"?

The key indicated by "W" represents the direction that is typically associated with the compass rose in railway and engineering contexts. In this specific instance, "W" stands for "West." Therefore, if the key is marked with "W," it signifies that the items or locations identified are in the western direction relative to the key switch located on track G.

Understanding this directional indication is crucial in navigation and layout planning, as it informs engineers and operators where specific components or actions pertain to the system being managed. The association of letters with cardinal directions is a standard practice in maps and schematics, thereby aiding in clear communication of positional information.

In this case, the correct answer emphasizes the significance of directional understanding in relation to railway system operations.