What is the output line

The output line is an imaginary line connecting the front edges of the staircase steps in the theoretical axis of the output.  Step heights are the same in one arm, the widths are always the same on the output line. The slope is 35 degrees for residential and civil buildings.  Stair treads with passage widths above 1801 mm have an exit line in the middle of the stairwell to make the most space available for stairwells.  For a four-arm arm, the position of the output line is according to the width of the staircase.  On the spiral staircase, the exit line is positioned 300 mm from the outer edge of the arm curvature.  The standard ČSN 73 4130 determines that the staircase should be of a designed dimension. In degrees with a curved output line, the width of the degree is measured as the arc of the arc at the point of intersection of the output line with the edges of the successive steps.