Understanding Call Numbers: Classification Scheme

Different classification schemes

If you do not have a specific title in mind, you may just want to browse the collection and pick up a book or DVD that catches your attention. To facilitate this type of browsing, materials on the same subject are shelved together.

The following table shows the subject classification schemes the Library uses for English and Chinese materials. Click on the names of the classification schemes to learn more about the schemes get an idea of what call number ranges you might like to browse.

Call number length and subject specificity

If you want to look for something more specific, you should browse forward, i.e. to find longer call numbers. If you want to look for something more general, you should browse backward, i.e. to find shorter call numbers. A more specific subject will have a longer, more complicated call number, and a less specific (i.e. more general) subject will have a shorter, simpler call number. The following table explains this relationship.

The above example is from the Dewey Decimal system of classification.

Note that LC call numbers generally do not reflect the above relationship in a hierarchical sense. A longer LC call number does not necessarily mean a more specific subject area, and vice versa. That means that you may want to browse through the whole range of books that bear the LC class letters for the subject you are interested in.