Excerpt: "The outliers in this case are those elements that appear in a large number of records — that is, what might be considered “core” elements that are used to describe the vast majority of library owned material. Those “outliers” can be categorized according to three general purposes: * Provenance and Identity: identifiers (e.g. ISBN, OCLC, etc.) and cataloging source (040); * Elements useful for discovery: title statement (245), personal names (100, 700) and subject (650); * Elements useful for understanding and evaluation: publication statement (260), physical description (300), and notes (500). That’s it. In a nutshell you have the very core of bibliographic description as defined by librarians over the last century or so." - Peter Murray

Y'know, this was true when I published a large-scale set of numbers in Bibliographic Displays in the Online Catalog in 1986; somehow, it's not surprising that it's still true in 2010. - Walt Crawford