Flow Diagrams: Rise and Fall of the First Software Engineering Notation

Drawings of water are the earliest, least abstract forms of flow diagram. Representations of ideal or generalised sequences for manufacturing or actual paths for materials between machines came next. Subsequently documentation of production and information flow become subjects for graphical representation. A similar level of abstraction was necessary for representations of invisible flows such as electricity. After initial use to define control, flow diagrams became a general purpose tool for planning automated computation at all levels of composition. Proliferation of syntax variants and the need for a common language for documentation were the motivations behind standardisation efforts. Public communication of metalevel systems information superseded private comprehension of detailed algorithmic processes as a primary function. Changes to programming language structures and their associated processes caused the initial demise of flow diagrams in software engineering.