This guide specifies recommended scales for architectural, building product, and building drawings using metric (SI) units of measurement, and measured with scale instruments graduated in millimetres. Careful consideration should be given to the selection of suitable scales in metric building drawings. Scales for use with metric (SI) drawings are expressed as ratios only. For the purpose of classifying suitable scale ratios, the following drawing types shall be identified: area location plan; block plan; site plans; general location drawings; component drawings; assembly drawings; and component detail drawings.