1xx The 1XX fields in MARC21 records primarily contain information about the main entry, which typically represents the primary creator or contributor of the bibliographic resource. Here's a breakdown of the 1XX fields with subfields commonly used along with an example: 100 - Main Entry-Personal Name : Indicators : Indicator 1 specifies whether the personal name is established in the Library of Congress Name Authority File (value "0") or not established (value "1"). Subfield $a : Personal name (Example: Rowling, J.K.) Subfield $b : Numeration (Example: III) Subfield $c : Titles and other words associated with a name (Example: Sir) 110 - Main Entry-Corporate Name: Indicators : Indicator 1 specifies whether the corporate name is established in the Library of Congress Name Authority File (value "0") or not established (value "1"). Subfield $a : Corporate name (Example: Library of Congress) Subfield $b : Subordinate unit (Example: Cataloging Policy and Support Office) 111 - Main Entry-Meeting Name: Indicators : Indicator 1 specifies whether the meeting name is established in the Library of Congress Name Authority File (value "0") or not established (value "1"). Subfield $a : Meeting name (Example: International Conference on Machine Learning) Subfield $n : Numbering (Example: 28th) Subfield $d : Date of meeting (Example: 2021) Subfield $c : Location of meeting (Example: New York, N.Y.) 130 - Main Entry-Uniform Title: Indicators : Indicator 1 specifies whether the uniform title is established in the Library of Congress Name Authority File (value "0") or not established (value "1"). Subfield $a : Uniform title (Example: Bible. New Testament. Greek)