ISO_prep_id
prepid = (char *)ISO_prep_id(h->iso_buf);
prepid = (char *)ISO_prep_id(h->unix_buf);
copystring(prepid, (char *)ISO_prep_id(unix_buf), 128);
copystring(prepid, (char *)ISO_prep_id(iso_buf), 128);
prepid = (char *)ISO_prep_id(iso_buf);
prepid = (char *)ISO_prep_id(unix_buf);
#define ISO_PREP_ID(x) ISO_prep_id(x)