Editing Undocumented feature (section)

== Software == 
Undocumented features (for example, the ability to change the [[Switch (command line)|switch]] character in [[MS-DOS]], usually to a [[hyphen]]) can be included for [[computer compatibility|compatibility]] purposes (in this case with [[Unix]] utilities) or for future-expansion reasons. However; if the software provider changes their software strategy to better align with the business, the absence of documentation makes it easier to justify the feature's removal.

New versions of software might omit mention of old (possibly superseded) features in documentation but keep them implemented for users who've grown accustomed to them.<ref name="Arredondo_1984"/>

In some cases, [[software bug]]s are referred to by developers either jokingly or conveniently as undocumented features.<ref name="Carr_2018"/><ref name="Dourish"/> This usage may have been popularised in some of Microsoft's responses to bug reports for its first [[Word for Windows]] product,<ref name="Gleick_1984"/> but does not originate there. The oldest surviving reference on [[Usenet]] dates to 5 March 1984.<ref name="FirstUse_1984"/> Between 1969 and 1972, Sandy Mathes, a systems programmer for [[PDP-8]] software at [[Digital Equipment Corporation]] (DEC) in Maynard, MA, used the terms "bug" and "feature" in her reporting of test results to distinguish between undocumented actions of delivered software products that were ''unacceptable'' and ''tolerable'', respectively. This usage may have been perpetuated.<ref name="Mathes_2010"/>

Undocumented features themselves have become a major feature of [[computer game]]s. Developers often include various [[cheat code|cheat]]s and other special features ("[[Easter egg (media)|easter egg]]s") that are not explained in the packaged material, but have become part of the "buzz" about the game on the [[Internet]] and among gamers. The undocumented features of foreign games are often elements that were not [[language localization|localized]] from their native language.

[[Closed source]] [[application programming interface|API]]s can also have undocumented functions that are not generally known. These are sometimes used to gain a commercial advantage over third-party software by providing additional information or better performance to the application provider.