MARC 21 Format for Holdings Data

Chronology and Enumeration Types with Code Patterns

Network Development and MARC Standards Office
Library of Congress

$y ­ Regularity Pattern

Subfield $y contains codes that describe the regularity of the publishing pattern coded in subfield $w (Frequency). The subfield may be structured in two ways using either chronology or enumeration code values. Both types begin with a publication code.

Publication Code

Chronology Code

<Publication Code><Chronology Code Definition><Chronology Code>,<Chronology Code>,...

The subfield may contain one or more chronology codes that are associated with the publication code and chronology code definition that are in the first and second character position of the subfield. The subfield may be repeated to allow for coding more than one publication code/chronology code definition/chronology code string to indicate regular exceptions to a specified regularity pattern (i.e. normalized irregulars).

Chronology Code Definition - The second one-character code in the subfield indicates whether the subsequent Chronology Code(s) represent the name of a day, a numeric month or month and day code, a code for a season of the year, or a code for a week of the month or year. If the subfield describes regularity in terms of enumeration, this code is "e."

Chronology Code - The chronology code in the chronology type indicates the designation of the part of the item for which regularity pattern information is provided. Multiple codes are separated by a comma. A slash (/) is used to designate combined issues.

Two-character alphabetic or numeric codes are used for days, weeks, months, and/or seasons. A four character code is used to indicate a year or year combination. A code of less than two digits is right justified and the unused position contains a zero.

Chronology Type and Code Patterns

Pattern Description

Pattern Values

Enumeration Code

<Publication Code><Enumeration Code Definition>,<Enumeration Code><Enumeration Code>,...

An enumeration code may occupy the second and third positions after subfield $y to provide for regularity patterns for items that use only enumeration for sequencing and/or those items whose sequencing must be specified separately when combinations occur.

Enumeration code definition - The second code in the subfield indicates whether the subsequent codes represent enumeration rather than chronology. When code "e" is used, an additional numeric code is added to indicate the level of enumeration to which the regularity applies.

Enumeration code - The enumeration code following the enumeration code definition indicates the designation of the issues of the item for which regularity pattern information is provided. Multiple designations are separated by a comma. A slash (/) is used to designate a combined issue.

The presence of continuous numbering (subfield $v, code c) in conjunction with an enumeration code signals the combination of specific numbers in the sequence of specific issues. Because of the continuous numbering, the actual enumeration values cannot be used to express the enumeration in subfield $y. Enumerative values must be represented in terms of the number of issues expected to be published to allow combined issue prediction to occur.

Automated systems may construct algorithms to predict the second level of continuous enumeration based on the starting value of the second level of enumeration at the beginning of the subscription cycle.

The regularity pattern codes are maintained at the Library of Congress. Questions on coding patterns or establishing new ones should be addressed to the Network Development and MARC Standards Office, Library of Congress, Washington, D.C. 20540-4402 (E-mail: ndmso@loc.gov).

Examples