L6 : OPTIONAL argument position

Optional arguments to a routine shall be after non-optional ones.

To be avoided :

OPTIONAL argument position

SUBROUTINE OPT_ARG( ARG1, ARG2, ARG3)

INTEGER(KIND=JPIM), INTENT(IN)          :: ARG1
INTEGER(KIND=JPIM), INTENT(IN),OPTIONAL :: ARG2
INTEGER(KIND=JPIM), INTENT(OUT)         :: ARG3