Identify a record, segment, field, or data element (i.e., to differentiate one logical data component from another).
Search for a resource corresponding to stated criteria (i.e., to search either a single entity or a set of entities using an attribute or relationship of the entity as the search criteria).
Identify a resource (i.e., to confirm that the entity described or located corresponds to the entity sought, or to distinguish between two or more entities with similar characteristics).
Select a resource that is appropriate to the user’s needs (i.e., to choose an entity that meets the user’s requirements with respect to content, physical format, etc., or to reject an entity as being inappropriate to the user’s needs).
Access a resource either physically or electronically through an online connection to a remote computer, and/or acquire a resource through purchase, licence, loan, etc.
Control access to or use of a resource (i.e., to restrict access to and/or use of an entity on the basis of proprietary rights, administrative policy, etc.).
Manage a resource in the course of acquisition, circulation, preservation, etc.
Operate a resource (i.e., to open, display, play, activate, run, etc. an entity that requires specialized equipment, software, etc. for its operation).
Interpret or assess the information contained in a resource.
Identify a record, segment, field, or data element (i.e., to differentiate one logical data component from another).
Process a record, segment, field, or data element (i.e., to add, delete, replace, output, etc. a logical data component by means of an automated process).
Sort a field for purposes of alphabetic or numeric arrangement.
Display a field or data element (i.e., to display a field or data element with the appropriate print constant or as a tracing).
The Functional Requirements for Bibliographic Records (FRBR) document's main part defines the primary and secondary entities which became famous as FRBR models. Years later Tom Delsey created a mapping between the 12 functions and the individual MARC elements.
Tom Delsey (2002) Functional analysis of the MARC 21 bibliographic and holdings formats. Tech. report, Library of Congress, 2002. Prepared for the Network Development and MARC Standards Office Library of Congress. Second Revision: September 17, 2003. https://www.loc.gov/marc/marc-functional-analysis/original_source/analysis.pdf.
This page shows how these functions are supported by the records. The horizontal axis show the strength of the support: something on the left means that support is low so only small portion of the fields support a function are available in the records, something on the right means the support is strength. The bars represents a range of values. The vertical axis shows the number of records having values in the same range.
It is experimental because it turned out, that the the mapping covers about 2000 elements (fields, subfields, indicatiors etc.), however on an average record there are max several hundred elements, which results that even in the best record has about 10-15% of the totality of the elements supporting a given function. So the tool doesn't shows you exact numbers, and the scale is not 0-100 but 0-[best score] which is different for every catalogue.