Physics · Engineering Drawing

Which of the following statements correctly describes the placement and purpose of orientation marks on a drawing sheet? 1. Orientation marks are placed at two opposite corners of the drawing sheet to indicate the correct orientation on the drawing board. 2. Orientation marks consist of arrow heads placed across the frame, with one at the shorter side and one at the longer side, coinciding with the centering marks. 3. One of the orientation marks always points towards the draughtsman, indicating the direction in which the drawing sheet should be placed. 4. Orientation marks are used to mark the midpoint of each side of the drawing sheet for accurate centering.