In the Vienna Convention's A-H road-sign classes, what does category A cover?

In the Vienna Convention’s A–H road-sign classes, category A covers danger warning signs.

The Vienna Convention on Road Signs and Signals is an international treaty that standardises important features of road signs, traffic lights and road markings. It was agreed in Vienna on 8 November 1968 and entered into force on 6 June 1978. Its classification system groups signs by purpose rather than by the individual hazard shown.

Category A is the warning class: it covers signs that alert road users to dangers ahead, such as bends, junctions, steep descents, roadworks or crossings. Convention warning signs are commonly triangular with a contrasting border, although the agreement permits some national variation, including diamond-shaped warning signs in certain systems.

The remaining classes are easy to confuse. B covers priority signs, C prohibitory or restrictive signs, D mandatory signs, E special regulation signs, F information or service signs, G direction or indication signs, and H additional panels. Thus, a supplementary plate beneath a warning sign belongs to H, while the principal warning sign itself belongs to A.