What is a standee line on a bus, and where does it fall?

Explanation

A standee line is a line of contrasting color at least 2 inches wide, or some other equivalent means, marking off the area forward of a perpendicular plane drawn through the rear of the driver's seat, and riders may not stand ahead of it. 49 CFR 393.90 requires that marking on buses designed to allow standees, along with a sign at or near the front in letters at least one-half inch high stating that operating with persons in the prohibited area violates Federal Motor Carrier Safety Administration regulations, and 49 CFR 392.62(a) makes it the driver's own duty by barring anyone from driving a bus unless all standees are rearward of that line. The rule is about standing rather than occupancy: 393.90 permits permanent seats in that forward area where their seated occupants will not interfere with the driver's safe operation of the bus, so a seated rider ahead of the line is not the violation, a standing one is. The wrong options change either the geometry or the meaning, since the width is 2 inches and the reference point is the rear of the driver's seat rather than the first row of seats, and the line marks a no-standing boundary rather than a certified standing capacity or a queueing mark at the rear door.

Source: 49 CFR 393.90