If "lovebirds" are a member of the parrot (636.6865) family, why don't they have a number like cockatiels (636.68656)? In other words, why aren't they one level lower in the parrot hierarchy?

The usual Dewey method of showing hierarchical relationships is by use of subordinate numbers with indented headings. We may, however, also show subordination by use of a see reference. You will find a reference under the parrot number to the coordinate subdivision of the finches/parrots/hawks number used for Budgerigars, that is, from 636.6865 to 636.6864.

Last revised: 18 November 2003