This standard specifies the size limits for the installation of smart toilet covers and tank-less bases, and the size limits for the installation of smart toilet covers and water tank-type bases. The index names include: installation hole diameter, installation hole center line The spacing, the offset tolerance of the center line of the mounting hole, the thickness of the embryonic body around the mounting hole, the distance from the center line of the mounting hole to the front end of the base seat ring, the width of the base seat ring, the center line of the arc-wrapped seat ring mounting hole with a radius of l is determined by the vertical plane Go to the angle between point P where it intersects the wall.