予約語？なにそれ、食えるの？

PROGRAM PROGRAM
REAL REAL(8), THEN, END
IF(N) = N * 2
WRITE(I, A) = I + A
SIN(X) = COS(X)

THEN = 3.
REAL(4) = 1.2
END = 0.

WRITE(*,*) IF (1 + 2), THEN
WRITE(6,*) WRITE(6, 2.3), REAL(4), SIN(END)
STOP
END