Position engineering, also known as "position defense engineering". In order to complete combat missions, the army transforms the terrain and builds various fortifications, obstacles, roads, etc. in the selected or occupied areas to form an engineering system. It is divided into permanent position engineering and field position engineering. Permanent position engineering is based on tunnels and excavated permanent fortifications, combined with field fortifications, obstacles and military roads, and is used for long-term defense. Field position engineering is mainly based on the use and transformation of terrain and the construction of field fortifications, combined with obstacles and hastily built military roads, and is used for hasty defense, short-term defense, mobile defense and position attack.