1 A 1.8-metre (6-ft) length of signal line with signal clips, known as inglefield clips, at each end. It is used, mainly in naval vessels, for inserting in a flag signal hoist to indicate a break in the signal, and that the flags below it form a new signal. All flags used in signals at sea have an inglefield clip at each end of the hoist so that they can be clipped quickly to each other to form a particular signal; those on the tackline are of the same pattern and can be clipped equally quickly to signal flags when it is required to insert a break in the hoist. See also international code of signals.
2 A rope, or ‘tack’, used to control the lower corner of a course when a square-rigged ship is going to windward.