Source : Free On-Line Dictionary of Computing

data flow
     
        A data flow architecture or language performs a computation
        when all the {operand}s are available.  Data flow is one kind
        of {data driven} architecture, the other is {demand driven}.
        It is a technique for specifying parallel computation at a
        fine-grain level, usually in the form of two-dimensional
        graphs in which instructions that are available for concurrent
        execution are written alongside each other while those that
        must be executed in sequence are written one under the other.
        Data dependencies between instructions are indicated by
        directed arcs.  Instructions do not reference memory since the
        data dependence arcs allow data to be transmitted directly
        from the producing instruction to the consuming one.
     
        Data flow schemes differ chiefly in the way that they handle
        {re-entrant} code.  Static schemes disallow it, dynamic
        schemes use either "code copying" or "tagging" at every point
        of reentry.
     
        An example of a data flow architecture is {MIT}'s {VAL}
        machine.