Requirements Tracing on Target (RETRO) is software for after-the-fact tracing of textual requirements to support independent verification and validation of software. RETRO applies one of three user-selectable information-retrieval techniques: (1) term frequency/inverse document frequency (TF/IDF) vector retrieval, (2) TF/IDF vector retrieval with simple thesaurus, or (3) keyword extraction. One component of RETRO is the graphical user interface (GUI) for use in initiating a requirements-tracing project (a pair of artifacts to be traced to each other, such as a requirements spec and a design spec). Once the artifacts have been specified and the IR technique chosen, another component constructs a representation of the artifact elements and stores it on disk.

Next, the IR technique is used to produce a first list of candidate links (potential matches between the two artifact levels). This list, encoded in Extensible Markup Language (XML), is optionally processed by a "filtering" component designed to make the list somewhat smaller without sacrificing accuracy. Through the GUI, the user examines a number of links and returns decisions (yes, these are links; no, these are not links). Coded in XML, these decisions are provided to a "feedback processor" component that prepares the data for the next application of the IR technique. The feedback reduces the incidence of erroneous candidate links. Unlike related prior software, RETRO does not require the user to assign keywords, and automatically builds a document index.

This program was developed by Jane Hayes, Alex Dekhtyar, Senthil Sundaram, and Sravanthi Vadlamudi of the University of Kentucky for Goddard Space Flight Center. For further information, access the Technical Support Package (TSP) free online at under the Software category. GSC-14976-1.

NASA Tech Briefs Magazine

This article first appeared in the December, 2006 issue of NASA Tech Briefs Magazine.

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