
Unimplemented:
    * fits_iterate_data
    * fits_open_memfile
    * fits_split_names

Documented, but unavailable:
    * fits_calc_col
    * fits_get_imagecell_wcs_keys

Undocumented, but implemented:
    * fits_write_col_null
    * fits_read_col_bit

Other:
    * fits_hdr2str - exclude, nexc parameters unimplemented, they are
