The generality of define

[Bill Rozas <JINX%OZ.AI.MIT.EDU@XX.LCS.MIT.EDU>]

  (define square (lambda (x) (* x x)))

at all, but rather to

  (define square (rec square (lambda (x) (* x x))))

The new version of RRRS changes this.

(define (square x) (* x x))

will be equivalent to

(define square (lambda (x) (* x x)))

The self recursive form can be obtained by explicitely using LETREC or
wRECk.