Type: 1nil

An argument or return that is described as 1nil is a boolean flag that returns 1 for true and nil for false. These value can be tested using the basic if not flag then test, however they cannot be listed as boolean since if flag == true will not work.

Type: layer

One of the graphical layers present in World of Warcraft (presented from lowest to highest). Any graphics on the HIGHLIGHT layer are only displayed when the mouse is over the parent frame.