Functional flow block diagram: Difference between revisions

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[[Image:Functional Flow Block Diagram Format.jpg|thumb|420px|Figure 1: Functional flow block diagram format.<ref name="SEF01">[http://www.dau.mil/pubscats/Pages/sys_eng_fund.aspx ''Systems Engineering Fundamentals.''] {{webarchive|url=https://web.archive.org/web/20110728000913/http://www.dau.mil/pubscats/Pages/sys_eng_fund.aspx |date=2011-07-28 }} Defense Acquisition University Press, 2001</ref>]]

A '''functional flow block diagram''' ('''FFBD''') is a multi-tier, time-sequenced, step-by-step flow diagram of a [[system]]’s's functional flow.<ref>The first version of this article is completely based on the [http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/operations/sysengsaf/seman/SEM3.1/Section%204.4.pdf NAS SYSTEM ENGINEERING MANUAL SECTION] 4.4 VERSION 3.1 06/06/06.</ref> The term "functional" in this context is different from its use in [[functional programming]] or in mathematics, where pairing "functional" with "flow" would be ambiguous. Here, "functional flow" pertains to the sequencing of operations, with "flow" arrows expressing dependence on the success of prior operations. FFBDs may also express input and output data dependencies between functional blocks, as shown in figures below, but FFBDs primarily focus on sequencing.

The FFBD notation was developed in the 1950s, and is widely used in classical [[systems engineering]]. FFBDs are one of the classic [[business process modeling]] methodologies, along with [[flow chart]]s, [[data flow diagram]]s, [[control flow diagram]]s, [[Gantt chart]]s, [[PERT]] diagrams, and [[IDEF]].<ref name="TD03">Thomas Dufresne & James Martin (2003). [http://mason.gmu.edu/~tdufresn/paper.doc "Process Modeling for E-Business"] {{webarchive |url=https://web.archive.org/web/20061220024049/http://mason.gmu.edu/~tdufresn/paper.doc |date=December 20, 2006 }}. INFS 770 Methods for Information Systems Engineering: Knowledge Management and E-Business. Spring 2003</ref>