Trailing x in Call Numbers
Reviewed for currency, 19 February 2003 version information

RATIONALE: The reason for using a trailing x in locally assigned call numbers is to avoid the possibility that a number might be duplicated by a Library of Congress 050 number for a different title on a subsequently received record. If that happens, the trailing x will serve to differentiate the call numbers, and no reclassification will be necessary (unless it is desirable for other reasons).

BACKGROUND: Prior to 1990, Widener practice was to place the x after the final cutter and before the date, if any. In March 1990, the present practice of placing the x after the date was adopted, primarily to ensure correct filing and shelving by date when there is a sequence of items on the same call number differentiated only by date and some of the items have an x while others do not. Items cataloged under the previous practice should not be routinely corrected.

Procedures:

• For locally assigned Library of Congress call numbers, add a lower case x after the date, or after the date plus work letter. In the case of serials or serial analytics where there is no date, add the x at the end of the last cutter.
  
  (Note: Government Documents in Lamont has followed a special practice for the 1990 US Census: In order to create a logical subarrangement, work letters are added after the trailing x, e.g. |i doc |c Ref |a HA 201 |b 1990xab, etc.)
  

• If we are locally cataloging a supplement to a work which is on a Library of Congress 050 call number, it is not necessary to add an x anywhere.

*Originally issued as Widener Library Cataloging Documentation, Classification Memo CL/1996/8 by the Executive Committee of the Cataloging Council, 6 December 1996. Prepared by: Peter Lisbon. Reviewed for currency: Bruce Trumble, 19 February 2003.

Replaces memo of 1 March 1990 and earlier memos.