A simple SUBROUTINE takes the form:
SUBROUTINE name(list of arguments)
argument types
declaration of local variables
body of subroutine
END [SUBROUTINE [name] ]
A subroutine is called by using a CALL statement. For example:
PROGRAM Prog4
INTEGER a
CALL sub(2,a)
CONTAINS
SUBROUTINE sub(m,n)
INTEGER m,n
n=m+1
END SUBROUTINE sub
END PROGRAM Prog4
If flow control statements and/or constructs are used within the body of the subroutine then a RETURN statement can be used to exit from the subroutine. The END statement implies RETURN.