Input (grade 13): From July 1940 coastal shipping convoys and shipping centres, such as Portsmouth, were the main targets; one month later the Luftwaffe shifted its attacks to RAF airfields and infrastructure.
Output (grade 8): From July 1940 coastal shipping convoys and shipping centres, such as Portsmouth, were the main targets. A month later the Luftwaffe shifted its attacks to RAF airfields and infrastructure (other useful war targets).