45) What is the process of sinking the edge of one piece of timber to another by cutting grooves across its grains?

46) Which is used to subdivide a door or window with a vertical member of a frame?

47) What is a depression / recess inside the doorframe to receive the shutter?

48) What is the relationship of width of door and H height of door?

49) What is the size of opening for designation ?6 WS 12??