A language design for concurrent processes
Lawrence G. Tesler, Horace Enea · 1968
In conventional programming languages, the sequence of execution is specified by rules such as:(1) The statement GO TO is followed by the statement labelled L (Branching rule).(2) The last statement in the range of an iteration is followed, under certain conditions, by the first statement in the range (Looping rule).(3) The last statement of a subroutine is followed by the statement immediately after its CALL (Out-of-line code rule).... (Other rules)(n) In other cases, each statement is followed by the statement immediately after it (Order rule).