The Library of Congress began to print catalog cards in 1898 and began to distribute them in 1901. The Library of Congress Card Number was the number used to identify and control catalog cards. With the development of the MARC format and the first distribution of machine-readable records for book materials in the late 1960s, the name of the LCCN was changed to Library of Congress Control Number. LCCNs are used for authority, bibliographic and classification records and are currently structured as follows:
Element Length Positions
Alphabetic Prefix 3 00-02
Year 2 03-04
Serial Number 6 05-10
Supplement Number 1 11
The uniqueness of the LCCN is determined by the first 11 positions (positions 00-10). The Supplement Number has never been used by the Library of Congress and this position is always blank. The Supplement Number may be followed by two kinds of variable length data known as Suffix/Alphabetic Identifier and Revision Date. Each Suffix/Alphabetic Identifier is preceded by a slash as is Revision Date. If there is no Suffix/Alphabetic Identifier, the Revision Date is preceded by two slashes. Examples:
###95156543# May be displayed as: 95-156543 ###94014580#/AC/r95 May be displayed as: 94-14580/AC/r95 ###79310919#//r86 May be displayed as: 79-310919//r86 gm#71005810# May be displayed as: gm71-5810
For more details on the current and future structure of the Library of Congress Control Number, see the Structure of the Library of Congress Control Number.
INTERIM SOLUTION
With the year portion of the LCCN stated as two digits, there is no means of distinguishing numbers
assigned in different centuries, e.g., 98-1, and therefore the numbers duplicate one another. As an
interim solution to this problem, the Library has taken steps to minimize the possibility that LCCNs
assigned in 1898, 1899, 1900, etc. are re-assigned in the years 1998, 1999, 2000, etc. This is not a
significant group of numbers for the years 1998, 1999, and 2000 because fewer than 8000 numbers
were assigned in each of the years 1898, 1899, and 1900. However, beginning in 1901, the group of
numbers increases substantially.
With respect to "blocks" of Serial Numbers, the Library's current practice is to allocate the first
100,000 numbers in each year to the Cataloging in Publication Division (CIP). This will change
slightly in 1998 and 1999 in that the first CIP numbers assigned in these years will be greater than the
last Serial Number assigned in 1898 or 1899 (this approach will be followed as long as the interim
solution is in place at the Library).
LONG-TERM SOLUTION (RESTRUCTURE LCCN)
Although the interim solution could probably be managed for several years into the twenty-first century, the Library recognizes that this is not an adequate long-term solution. Therefore, the Library has decided to restructure newly assigned LCCNs such that the prefix portion will be reduced to two positions, and the year portion will be expanded to four digits (e.g., ##2000000001). There will no longer be a position defined for "Supplement Number," and use of the variable data elements Suffix/Alphabetic Identifier and Revision Date will be discontinued. The new structure will be:
Element Length Positions
Alphabetic Prefix 2 00-01
Year 4 02-05
Serial Number 6 06-11
Examples: ##2005256543 May be displayed as: 2005-256543
##2010014580 May be displayed as: 2010-14580
gm2005005810 May be displayed as: gm2005-5810
If the Library is able to implement the new LCCN structure by the year 2000, only the relatively few numbers assigned in 1898 and 1899 would not be readily distinguishable from those assigned in 1998 and 1999. If the implementation occurs later, numbers assigned in 1900, 1901, etc. would not be readily distinguishable from those assigned in 2000, 2001, etc.
Some of the considerations in choosing this alternative are:
For more details on the current and future structure of the Library of Congress Control Number, see the Structure of the Library of Congress Control Number.
TIMING OF THE RESTRUCTURING
The Library is well aware of the impact this change will have on other systems and is, therefore, attempting to provide adequate lead-time.
The actual date for implementing this change has now been set at January 1, 2001.
COMMENTS/QUESTIONS/SUGGESTIONS
Please send any comments, questions, or suggestions to:
Cataloging Policy and Support Office
Library of Congress
Washington, D.C.
20540-4305
Electronic mail address: cpso@loc.gov
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