2.33 Overview to MARC 21 Bibliographic Fields 001 & 003
Fields 001 and 003 are more fully documented by the Library of
Congress at http://lcweb.loc.gov/marc.
For this software, fields 001 and 003 are used as unique
bibliographic identifiers, along with the ISBN, ISSN, and LC
number. Thus, these important values help the software to look
up and possibly merge imported bibs.