Pro and Architectural
This command draws a construction line midway between 2 points and perpendicular to them. So for example if the 2 points indicated were the end points of
an existing line then the new construction line would be drawn through the mid-point of that line at 90 degrees to it.
button and the command prompt reads:
Use any of the snaps and input options
to indicate 2 points. A line three times the width of the current
is drawn. This is drawn on a layer called 'Constructions' which is set to 'blue' by default.