Data format of MARC 21
(i) Bibliographic Data Format: contains format for encoding data elements needed to describe, retrieve and control various forms of bibliographic materials
(ii) Holding Data Format: control format specification for encoding data elements pertinent to holding and location data for all forms of materials.
(iii) Authority Data Format: contains format specification for encoding data elements that identify and control the content related to authority control.
(iv) Classification Data Format: contains format specification for encoding data elements related to classification number and caption associated with.
