mitre line

• miter line (US)

mitre line (plural mitre lines)

1. (engineering) A line drawn marking an angle of 45 degrees, especially in the use of aligning the depth lines between the top and side views of a third angle projection technical drawing.
   • 1914, George R. Barham, Masonry: an Elementary Text-book for Students in Trade Schools and Apprentices, page 23:

     It is necessary to draw a line on the moulded surface which will be the intersection of the front and the return moulding. This line is known as a mitre line, and the intersecting arrises of the moulding, the mitre.

   • 2012, Dennis Dorn, Mark Shanda, Drafting for the Theatre, page 81:

     The most commonly used method for transferring depth measurements between the top and side views is through use of a 45° miter line, commonly known as the miter transfer system.

   • 2013, John Blurton, Scenery: Draughting and Construction for Theatres, Museums, Exhibitions and Trade Shows, page 159:

     Extend its relevant points across to the mitre line and then turn those lines at 90° to the mitre line and extend them. Mark the relevant height dimensions of the standard former from the mitre line along the new extended lines and the correct shape is obtained.