The following are common methods of identification:
White and yellow tabard (or in Scotland, red and white quadrants).
Red tabard.
Red and yellow tabard.
Blue and yellow tabard.
Red and white chequered tabard (may include yellow).
black and yellow chequered tabard.
Green and purple tabard.
Red and white chequered tabard with the reference, for example, HVP, NILO.
