A MARC 21 record may be encoded in 7-bit and 8-bit character sets or in the ISO Universal Coded Character Set (ISO 10646; UCS) (or Unicodeä, an industry subset).  ASCII is used for the structure elements of the record, with most coded data also specified within the ASCII range of characters.  More details on character sets, encoding, repertoires, etc., are provided in MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media.

See also:

Holdings Data Format:  Introduction