On headsail, length of line running from clew to luff, meeting luff at a 90 angle. Wire extension, usually detachable to stretch between sail and stem tack fitting or between sail and halyard shackle. Methods of reducing effective sail area. The adjustment of sail shape by changing the overlap of panel seams, for improvement. Very full shaped foot panel, usually of lighter cloth, which can be made fuller or flatter by adjusting outhaul tension.
Some sails have a zipper along the foot for the same purpose.
Sail has a wider than usual tabling to fit around the mast or stay, as a sleeve. Jibs with a luff sleeve can easily be converted to wire and hanks. A special headstay with grooves to accept jibs and genoas with a mating luff tape. Used on headsail luffs and luff and foot of mains. Increasing rope tension flattens the sail for brisk winds, relaxing the rope increases the fullness of the sail.