We need to build a DDC number for the Wollemi Pine. Paragraph 8.5 located in the Introduction of DDC 21 on p. xlvi (or in Help in WebDewey) gives the example of spiders in California and states that "The most important caveat with respect to standard subdivisions is that they are added only for works that cover or approximate the whole of the subject of the number." Does this mean that our number for the Wollemi Pine can only be: 585.3? It seems a shame not to be able to add the geographic subdivision as the Wollemi Pine is unique (so far) to a very specific region in the Blue Mountains. Can you please advise and let us know the reason for your verdict as this comes up from time to time.

Yes, you can only give 585.3 for the Wollemi pine, a member of the family Araucariaceae. In general you can only add standard subdivisions for topics that "approximate the whole" of a topic at a given DDC number. In this case 585.3 has the caption "Podocarpaceae, Araucariaceae, Cephalotaxaceae (plum-yew family)," and has an instruction: "Subdivisions are added for Podocarpaceae, Araucariaceae, Cephalotaxaceae together; for Podocarpaceae alone." So you could have 585.309944 for a book on Podocarpaceae in New South Wales, Australia, but for the other two families, and for the genera and species in any of the families, you can only use 585.3 without standard subdivisions.

The theory behind this is that if there are enough titles at a DDC number, we may expand at that number in the future (and also remove the topic from "standing room," which can be defined as those topics present in including notes). However, by saying that standard subdivisions may be added for Podocarpaceae, we are saying that even if there is an expansion for genera in that family, the number for Podocarpaceae is likely to remain 585.3.

Note also that the DDC is a subject classification, and in 580, the basic numbers are for kinds of plants. For most libraries it does not aid access to scatter works on specific kinds of plants in a large group among a span of geographic numbers. That would result in specific numbers, but they would be false specific numbers. If we can reasonably expect to need a number for a specific kind, we believe that libraries will be prepared to wait for the specific number for that kind.

We also accept the principle that in biology we need go no further than the genus number. Once we get a topic as specific as a genus, we doubt if it will serve much purpose to reserve room for species numbers except for rare species that have a large and distinct literature, like lions and tigers.

Last revised: 05 September 2003