There are no vertical symbols in the drawings of buildings, construction, electricity, water and facilities. In mathematical geometry, there is a vertical symbol with t written backwards.

Check whether the verticality and flatness are standard with a ruler. The flatness is on the wall, the upper wall and the lower wall. Measure two feet at the top corners on both sides of the wall and show them diagonally. The diagonal is the position of the guide ruler, and the deviation value is marked on the right side of the diagonal. The verticality of the measured vertical position is indicated by verticality symbol, and the verticality deviation value is marked on the right side. The vertical line position of the verticality symbol is the vertical position of the guide rule.