1.1 This guide covers unit sizes for clay and concrete masonry units laid in mortar for use in buildings and building systems designed in accordance with the principles of modular coordination. Specifically it covers: 1.1.1 Sizes of full-size u This guide covers unit sizes for clay and concrete masonry units laid in mortar for use in buildings and building systems designed in accordance with the principles of modular coordination. Specifically, it covers sizes of full-size units and supplemen