adding vernacular fields from marc records

Some MARC records for books in non-latin-based languages will have parallel fields: one for the transliteration into a latin-based character set, and one in the original (vernacular) character set. The languages covered in MARC to date are: Chinese, Japanese, Korean, Hebrew, Arabic, Cyrillic, Greek. In MARC records coming from US libraries, the transliterated information will be in the 'regular' MARC field (e.g. a transliterated title will be in a 245 field). The vernacular character will be in an 880. They are linked through the $6 subfield in both fields:

245 10 $6 880-02 $a Hung Jen-kan /$ccShen Wei-pin chu.
880 10 $6 245-02 $a[Chinese characters]

The $6 has the tag of the parallel field, and an incremented occurrence number. The key thing is the occurrence number - regardless of the field tag, the fields with the same occurrence number are linked. (The tag helps you figure out where to display them if you are displaying directly from the MARC record.)

There is nothing explicit in the fields to say which script is used. In theory, the 245 could be vernacular Chinese while the 880 could be transliterated, or even another character set. The language code in the MARC record could be clue, or one would need to use the Unicode range to determine the script (which is not totally accurate).