Question: Using define_external w/ Fortran Array

Hello,

I'm try to access some external Fortran routines within maple. I have a Fortran datatype of

  character*255 hf(20)

This is an input parameter, and I believe this will map into a maple Array object, but I'm not sure of the datatype. The help says that the datatype can only be "hardware datatypes" so I take to mean it would have to be of type integer[4]...when I do this I get the error below.

RefPropSetUp := define_external(
        'SETUPdll',
        'i'::integer[4],
        'hf'::ARRAY(datatype=integer[4]),
        'hfmix'::integer[4],
        'hrf'::string[3],
        'ierr'::integer[4],
        'herr'::string[255],
        'LIB'="C:\\Program Files\\REFPROP\\refprop.dll"
    );

hf:='nitrogen.fld'

Error, invalid input: RefPropSetUp expects its 2nd argument, hf, to be of type rtable(datatype = integer[4]), but received nitrogen.fld
 

Thank you...