LC Control Number Structure  (010 Library of Congress Control Number - Structure)

The LC control numbering system used with classification records has the same basic structure as that used in control numbers for Library of Congress bibliographic (LCCN structure A), authority, and holdings data records.  On January 1, 2001, a structural change occurred (LCCN structure B).  The basic control number has been fixed in length at 12 characters and will remain that length.  Under LCCN structure B, the location of element parts is slightly altered to accommodate a four digit year.

Note:  Under both structures, the alphabetic prefix, year, and serial number are the basic elements required to make an LCCN unique.

Alphabetic prefix:  (3 digits before January 1, 2001; 2 digits after)

Prefixes are carried in a MARC record as lowercase alphabetic characters and serve to differentiate between different series of LC control numbers.  Prefixes are left justified and each unused position contains a blank (#).  If no prefix is present, the prefix portion contains blanks.  LC classification records are differentiated from LC bibliographic, authority, and holdings data records by the control number prefix.

Examples:

010  ##  $acf#97051955#

[LCCN structure A; cf97-51955]

010  ##  $acf2001050268

[LCCN structure B; cf2001-50268]

Year:  (2 digits before January 1, 2001; 4 digits after)

For control numbers assigned under LCCN structure A, the year portion consists of two digits representing the year the control number was assigned.  For control numbers assigned under the LCCN structure B beginning with the year 2001, the year portion consists of four digits.

Serial number:  (6 digits before January 1, 2001; 6 digits after)

The serial number portion consists of one to six digits.  Serial numbers of less than six digits are right justified and each unused position contains a zero (0).  The hyphen separating the year and the serial number in LC printed products is not carried in the MARC record.  For example, the serial number in the number 85-2 is carried as 85000002.

To return, select:

010  Library of Congress Control Number