The Chandelier Exit is described in Dr. Alexander Elder's Book "Come into my Trading Room" and provides stops for closing long or short positions. It was originally conceived by Chuck LeBeau.
It accepts the number of bars to use for the calculation and a coefficient as parameters with 22 and 3 being the defaults that are also used in the examples in the book.
ChanUp should be used for long positions, ChanDn for short positions.