MARC 21 : BIBLIOGRAPHIC FORMAT
0XX - Control information ,numbers,codes
1XX = Main Entry
2XX = Titles and title paragraph (title, edition, imprint)
3XX = Physical description, etc.
4XX = Series statements
5XX = Notes
6XX = Subject access fields
7XX = Added entries other than subject or series; linking fields
8XX = Series added entries, etc.
9XX = Reserved for local implementation
