1 and National Standard for Mechanical Drawing (GB/T 15265- 1994) are national specifications for mechanical drawing technology, involving the requirements of composition, drawing, marking, marking, size and accuracy of technical drawings. It is not only an important standard to measure the quality of mechanical drawing, but also the basis for design, manufacture and maintenance of mechanical equipment.

2. The national standard "Technical Drawing" (GB/T 16494- 1996) is the national standard of technical drawing, which stipulates the requirements of composition, drawing, marking, dimension marking and accuracy of technical drawings. It is an important standard to measure the quality of technical drawings and an important reference for design, manufacture, maintenance and process improvement.