Formation signs at the division level were first introduced in the British Army in the First World War. They were intended (initially) as a security measure to avoid displaying the division's designation in the clear. They were used on vehicles, sign posts and notice boards and were increasingly, but not universally, worn on uniform as the War progressed. Discontinued by the regular army after 1918, only a few Territorial divisions continued to wear them before 1939. Reintroduced officially in late 1940 in the Second World War, divisional formation signs were much more prevalent on uniforms and were taken up by many other formations, independent brigades, corps, armies, overseas and home commands, military districts and lines of communication areas. The sign could be based on many things, geometry (simple or more complex), heraldry, regional or historical associations, a pun, the role of the division or a combination.