Draft it Help System
The complete Help system for Draft it is available on these pages.
Available in: Pro and Architectural
Select the button and the command prompt reads:
Give Point:
Use any of the snaps and input options to indicate the point you wish the to draw the horizontal construction line through. A horizontal line three times the width of the current page is drawn. This is drawn on a layer called 'Constructions' which is set to 'blue' by default.