Abstract: In order to adapt to the diversification of cataloguing objects, Universal Machine Readable
Cataloging (UNIMARC) Bibliographic Format Version 3 has been updated four times since its publication
in 2008. Three fields have been added to the “3XX Annotation Block” and 13 fields revised. Field names,
field definitions, indicators, sub-fields and so on were changed. Especially, many sub-fields have been
added with a unified resource identifier of $u, which means that bibliographic description based on
URI/ IRI identification resources will be expanded to other descriptive objects to actualize correlation.
The 3XX field covers almost all kinds of details and annotations of various documents. Making full use
of the detailed description of document details in sub-fields can help users to understand and retrieve
the relevant information of the required documents, and expand the scope and depth of information
retrieval.

Key words: UNIMARC, Bibliographic format, 3XX field, Annotation block