Use of the Small "x"
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Princeton University Cataloging Documentation

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  Cutter table
  .A6-.A99 table
  .Z5-.Z999 table
  Biography table
  Table XL

Size symbols
   See also: Miniature bks

Translation table

Use of small x

Preferred order for individual authors

See also:
Classification / Shelflisting policy

Use of the small "x"
At a time when Princeton was expanding the use of the LC classification system over Richardson, it was deemed wise to implement a device whereby Princeton-assigned LC call numbers could be distinguished from LC-assigned LC call numbers. This would obviate the need to check the shelflist before assigning new LC call numbers.

The device was to interpose a lowercase "x" just before the book number. Titles whose call numbers were differentiated only by the presence of the "x" would not be considered in conflict (see Duplicate Call Numbers).

This policy was adopted by the Division Heads on 25 July 1971 and ceased ca. 1984.

The "x" is ignored in shelving, shelf reading, and shelflist filing. If the same number appears with and without the "x", the number without the "x" comes first.




  • New titles never receive this "x"--even serial title changes when it was present in the call number of the earlier title (see Serial Call Number Decisions).
  • Call numbers are never changed simply to remove the "x"; however, if they are being changed for another reason, the "x" is dropped.
  • If a CAS number includes a small "x", it should be retained.