Inverse search is a feature of some non-interactive typesetting programs, such as LaTeX and GNU LilyPond. These programs read an abstract, textual, definition of a document as input, and converts this into a graphical format such as DVI or PDF. In a windowing system, this typically means that the source code is entered in one editor window, and the resulting output is viewed in a different output window. Inverse search means that a graphical object in the output window works as a hyperlink, which brings you back to the line and column in the editor, where the clicked object was defined. The inverse search feature is particularly useful during proofreading.