The original report was produced in 1969.
Dominant languages at the time were FORTRAN for scientific work
And COBOL for commercial programming.
The earlier Algol 60 was also around, but not widely used.
Algol 60 had been defined with accurate formal syntax (using BNF)
But with semantics described in English.
Algol 68 used a new technique for describing the semantics of the language.
report was revised
with experience of implementations of the language.