This study intends to investigate the processing of the bibliographic relationships in the MARC formats based on the analysis to the related cataloging rules. In the traditional cataloging rules, many methods are used to process the bibliographic relationships(vertical, horizontal, and chronological), including analytics, references, notes, and independent entry. Linking entry fields in the MARC formats have been introduced mainly to process the chronological relationship in the serials, but later expanded, as a chronological in MARC format, to include other relationships applied to all other materials. Comparative analysis on the linking entry suggests that there are rare differences between UNIMARC and USMARC formats except the terminology and display constants, and that it is desirable in the KORMARC and JAPAN MARC to introduce the linking entry more comprehensively.