fileopen Subroutine

subroutine fileopen(filename,lun,ier)

character(len=*),intent(in)   :: filename
integer,intent(out)           :: lun
integer,intent(out),optional  :: ier
integer                       :: ios
character(len=256)            :: message

    message=' '
    ios=0
    if(filename/=' ')then
        open(file=filename, &
        & newunit=lun, &
        & form='formatted', &    ! FORM    = FORMATTED | UNFORMATTED
        & access='sequential', & ! ACCESS  = SEQUENTIAL| DIRECT | STREAM
        & action='write', &      ! ACTION  = READ|WRITE| READWRITE
        & position='rewind', &   ! POSITION= ASIS      | REWIND | APPEND
        & status='new', &        ! STATUS  = NEW| REPLACE| OLD| SCRATCH| UNKNOWN
        & iostat=ios, &
        & iomsg=message)
    else
        lun=stdout
        ios=0
    endif
    if(ios/=0)then
        lun=-1
        if(present(ier))then
           ier=ios
        else
           call fpm_stop(3,'*fileopen*:'//filename//':'//trim(message))
        endif
    endif

end subroutine fileopen