DATE: February 2, 1995

NAME: Changes to the form of the Library of Congress Control Number (LCCN)

SOURCE: Library of Congress

SUMMARY: This paper discusses the change being planned by the Library of Congress to change the LCCN to avoid duplication of numbers in 1998 and future years.

KEYWORDS: Field 010 (Library of Congress Control Number)


2/95 - Sent to USMARC for comment. Copies taken to the USMARC Advisory Group meeting February 4 for distribution and comment.

DISCUSSION PAPER NO. 84: Changes to the Form of LCCNs


This paper discussions options that the Library of Congress is
considering to handle uniqueness of LCCNs as they enter their 2nd
century of numbers.  LCCNs are the control numbers used for
bibliographic and authority records distributed by LC.  LCCNs were
first known as Library of Congress Card Numbers and were used to
identify and control cards, which were first printed in 1898 and
first distributed in 1901.  The earliest card numbers date from
1898.  With the inception of the development of the MARC format and
the first distribution of machine-readable records for book
materials in the late 1960s, the meaning of LCCN was changed to
Library of Congress Control Number.


Currently, the LCCN is structured as follows:

      Alphabetic prefix                3     00-02
      Year                             2     03-04
      Serial number                    6     05-10
      Supplement number                1     11
The uniqueness of the LCCN is currently determined by the first 11
digits.  The Library of Congress has never implemented the
Supplement number concept; this position is always blank.

Upon distribution, LCCNs, may also include a variable length
alphanumeris suffix.  The suffix information does not affect the
uniqueness of the LCCN.

Examples:    ###94089743#


With the occurrence of the year 1998, there is a need to avoid
duplication of numbers assigned in 1898.  Within the Library of
Congress various technical solution are being considered that will
avoid duplication of any numbers within the current databases.  LC
is considering several approaches to the external view of the LCCN
so that it will continue to be useful to agencies that load LC


1.    Avoid numbers already used.  Internally the Library may simply
      avoid duplication by checking new numbers against the ones
      already in the file for the year prefix (e,g, for 98, 99, 00,
      etc.) and assign a number that has not been used.  This will
      avoid duplicates within the scope of the Library's databases. 
      The Library is currently considering whether the scope of this
      technical approach is enough, since it could be that some of
      the early LCCNs are not represented in the current LC
      database.  If this technical solution is followed internally,
      the structure of the number could remain the same, at least
      for a large number of years.  The century associated with the
      number will not be apparent with this approach.

2.    Expand year.  Expand the length of the LCCN by expanding the
      two-digit year to a four-digit year.  Under this approach, the
      new LCCN structure would be:

      Alphabetic prefix                3     00-02
      Year                             4     03-06
      Serial number                    6     07-12
      Supplement number                1     13

3.    Use position 11.  Redesign the use of the Supplement number
      position to be a Century designation which would use a letter
      of the alphabet to denote the first two-digits of a four-digit
      year.  Under this approach, the new LCCN structure would be: 

      Alphabetic prefix                3     00-02
      Year                             2     03-04
      Serial number                    6     05-10
      Century designation              1     11

      Current thinking suggests that the Century designation would
      be an alphabetic, perhaps defined as follows:

             # = 18 or 19 (i.e., as now)
             c = 20


While the LCCN is a local data element, it is known to be widely
used.  It is certain that the Library will need to change its
internal processing to handle the 2nd century of assignments of
this number.  To assist the Library in determining which is the
best option to pursue, LC would be interested in comments on the
user impacts of the various options.  Please send comments to

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Library of Congress Help Desk (09/03/98)