Final answer:
A combined overlay combines data like terrain and weather to aid in military planning by depicting effects on battlefield mobility.
Step-by-step explanation:
The overlay being described that combines more than one product to depict the effects on battlefield mobility is known as a combined overlay. This type of overlay is used in military context to provide a comprehensive view of different variables such as terrain, weather, and enemy positions, which can affect troop movement and logistics.
A combined overlay is a critical tool in military planning as it helps strategists visualize the integration of multiple factors to assist in decision-making.