Algol 60 was the first structured programming language containing blocks whose range defined the scope of variables, i.e. the variables declared within the block was accessible for code statements within that block only: begin integer A, X; comment outer X; A := 3; X := 5; begin integer X, Y; comment inner X; X := 4; comment inner X assigned here; Y := 8; end print (X); comment prints "5", not "4" since this is outer scope; Y := 12; comment illegal! Y not defined in outer scope; end;