While fortifications were evolving to the simpler polygonal style, the term was sometimes used to describe the flanking positions set at the corners of the ditch that provide the same function in that style of fort, especially in France.
It usually takes the form of a low passage, often partly sunken into the floor of the ditch and projecting outward into it, with access from the main fortress via a passage through the curtain wall, or as fortresses became largely underground, via a tunnel from within the fort.