Engineering revision control developed from formalized processes based on tracking revisions of early blueprints or bluelines. Implicit in this control was the option to be able to return to any earlier state of the design, for cases in which an engineering dead-end was reached in iterating any particular engineering design. Likewise, in computer software engineering, revision control is any practice which tracks and provides controls over changes to source code. Software developers sometimes use revision control software to maintain documentation and configuration files as well as source code. In theory, revision control can be applied to any type of information record. In practice, however, the more sophisticated techniques and tools for revision control have rarely been used outside software development circles (though they could actually be of benefit in many other areas)