A derivative of ALGOL 60. It introduced double precision, complex numbers, bit strings and dynamic data structures. It is parsed entirely by operator precedence and used the call-by-value-result calling convention.
["A Contribution to the Development of Algol", N. Wirth, CACM 9(6):413-431, June 1966].
["ALGOL W Implementation", H. Bauer et al, TR CS98, Stanford U, 1968].