Canceled class numbers are enclosed in brackets with the caption: [This number not used].
The National Library of Medicine cancels classification numbers from its schedules for a variety of reasons – most often classification numbers are realigned to better reflect their domain and improve collocation of materials on related concepts. In general, cataloged materials that used the now canceled class number are not reclassified and moved at NLM. Other libraries might choose to reclassify.
Generally, notes are added at the now obsolete number to redirect catalogers to the new number to be used for new materials. The Canceled Class Numbers (Cumulative List) indicates when a class number was made obsolete.
Note that [WW 113] and [This number not used] are both in brackets.
| Class Number | Caption |
|---|---|
| WW Ophthalmology Eye Anatomy. Physiology |
|
| [WW 113] | [This number not used] Classify prevention of vision disorders in WW 140.5; eye protective devices in WW 26. |