What does it mean that a fire door of the same size is also marked on the entrance of the civil air defense?

The door opening has been set in the defined door frame wall, so there is no need to draw the door component.

The so-called civil air defense door] is the civil defense protection equipment used by the government when carrying out a certain rescue operation. It is a door used for emergency air defense, such as the very heavy ones set up in the underground garages in the community. Doors filled with cement and doors of emergency shelters are all civil defense doors, used to protect people taking refuge and to block blasting and killing people. Anti-proof doors (protective airtight doors and airtight doors) are generally made of concrete and steel. The size ranges from 800 to 2000m wide, and the height is generally 2000m.