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

The first one-character code in both of the chronology and enumeration types indicates whether the subsequent codes refer to the publication or the nonpublication of part(s) of the item or the combination of either enumeration or chronology elements.

  c - Combined
o - Omitted
p - Published

Chronology Code

The chronology type is structured as:

<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."

  d - Day
m - Month
s - Season
w - Week
y - Year

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

Chronology Type Code Possible Chronology Code Pattern Example Example Meaning
d dd su Sunday
d DD 08 8th day of each month
m MM 09 September
d MMDD 0925 September 25
s SS 22 Summer
w WWdd 03we Third Wednesday
w MMWWdd 0599tu Last Tuesday in May
w MMWWdd 0802we Second Wednesday in August
w MMWW 1204 Fourth week in December
y YYYY yyy1/yyy2 Span over 2 years

Pattern Description

Pattern Meaning Characteristics Possible Values ­ Summary
DD day alpha mo-su
DD day numeric 01-31
ww week numeric 01-53
WW week numeric 99, 98, 97, 00, 01, 02, 03, 04, 05
MM month numeric 01-12
SS season numeric 21, 22, 23, 24
y year numeric 2002

Pattern Values

Week - WW
Day of week - DD
mo - Monday
tu - Tuesday
we - Wednesday
th - Thursday
fr - Friday
sa - Saturday
su - Sunday
Week of Month - WW
99 - Last
98 - Next to Last
97 - Third to Last
00 - Every
01 - First
02 - Second
03 - Third
04 - Fourth
05 - Fifth
Month - MM
Day of Month - DD
Season - SS
21 - Spring
22 - Summer
23 - Autumn
24 - Winter

Enumeration Code

The enumeration type is structured as:

<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.

  e1 - Enumeration, lst level
e2 - Enumeration, 2nd level

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:


854 03$81$a(year)$b(month)$c(day)$wd$yodsa
  [Item is published daily except Saturday.]
854 02$81$av.$bno.$u11$vr$i(year)$j(month)$wm$x01$ypm01,02,03,04,05,06,07/08,09,10,11,12
  [Item is a monthly, with the first number appearing in January and a combined July/August issue.]
854 03$81$av.$bno.$u10$vr$i(year)$j(month)$w10$x09$yom07,08
  [Item has ten numbers per volume; ten numbers per year beginning with no. 1 in September; no numbers published in July or August.]
854 03$81$av.$bno.$u4$vr$i(year)$j(month)$w4$x01$yps21,22,23,24
  [Item has four numbers per volume; four numbers per year, published in Spring, Summer, Autumn, and Winter]
853 03$81$av.$bno.$ww$yow0100we,0699we,0700we,0801we, 0802we,0803we,0804we,98we,99we
  [Publication is omitted all weeks of Jan. (01); last Wed. in June (0699we); every Wed. in July (0700we); 1st, 2nd, 3rd, and 4th Wed. in Aug. (0801we, 0802we, 0803we, 0804we); next to last Wed. (98we) and last Wed. (99we)]
853 20$81$av.$bno.$u48$vr$ww $x0101$yow05we
  [Item is a weekly, but omits the fifth Wednesday of the month.]
853 03$av.$bno.$u12$vr$i(year)$j(month)$wm$x01$ypw02we$ypw0402th,0501we
  [Item is monthly, published every second Wednesday of the month except in April when it is published on the second Thursday of May, when it is published on the first Wednesday.]
853 02$av.$bno.$u52$vr$wc$x07$ypw00mo,00th$yod0101,0704,1225$yow0901mo,1104th
  [Item is published every Monday and Thursday except for when New Year's Day, the fourth of July, Labor Day, Thanksgiving and Christmas fall on a Monday or Thursday.]
853 02$av.$i(year)$wg$ypyyyy1/yyy2
863 02$a10$i1999/2000
853 02$81.0$av.$bno.$u51$vc$i(year)$j(month)$ww$ycw1204/1205$yce251/52
[Item is published in fifty-one continuously numbered weekly issues. Issues dated in the fourth and fifth weeks of December (the fifty-first and fifty-second issues of the subscription year) are published in a combined issue.]
853 02$81.0$av.$bno.$u6$vr$i(year)$j(month)$wb$ype21,3,5,7,9,11
[Item is published six times per year whose enumeration "skips" numbers at the second level using only odd numbers that restart at the turn of the calendar year.]
853 02$81.0$av.$bno.$u12$vr$i(year)$j(month)$wm$yce27/8$ycm07/08
[This title is published eleven times per year, combines in its second level enumeration (for issues seven and eight) and combines chronology (July and August).]
853 02$av.$bno.$u6$vr$we$ypw02we,04we$yce21/3,4/6
[Item is published twenty-four times per year on the second and fourth Wednesdays of every month. The second level of enumeration combines numbers 1 to 3 on the second Wednesday of every month and numbers 4 to 6 on the fourth Wednesday of every month.]
853 02$81.0$av.$bno.$u52$vc$ww$yce251/52
[Item is published weekly except for a combination in the last two weeks of December. Since issue description is limited to enumeration only, and the second level enumeration is also continuous, the pattern represents the issue combination in terms of combining the fifty-first and fifty-second issues published that year.]
853 20$81.0$a(year)$b(month)$c(day)$ww$ycw1203/1204
[Item is published weekly except that it combines the third and fourth weeks in December.]
853 02$81.0$av.$bno.$u12$vr$i(year)$j(month)$wm$yce27/8$yom08
[Item is published eleven times per year with combined enumeration in July and no publication in August. The subfield is repeated for the enumeration exception as well as the chronology exception to the general regularity pattern.]
853 02$81.0$av.$bno.$u11$vr$i(year)$j(month)$w11$ycm07/08
[Item published eleven times per year with combined chronology and no combination in the enumeration.]

02$81.0$av.$bno.l$u92$vc$i(year)$j(month)$wd$x01,04,07,10$ycd0704/0705, 1224/1225 $yce2185/186,358/359$nBased on v. 11, no. 2172/2173, December 24/December 25, 2001.
[Item is published in three hundred and sixty-three continuously numbered issues in four volumes each year. Issues dated July 4th and December 25th are published as combined issues.]

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