ANSEL, American National Standard for Extended Latin Alphabet Coded Character Set for Bibliographic Use, is a character set used in text encodings like MARC-8. ANSEL is also known as ANSI/NISO Z39.47 or American Library Association character set (as used in library systems including the MARC format).
Rather than having precomposed characters like ISO-8859-1 it codes basic characters and a large number of combining diacritic marks, making it capable of expressing a large range of characters.
Read more about ANSEL: Use