I suspected that a multi/trans-disciplinary book like TDO was going to be hard to classify, but it is almost amusing to see how it is being done. I am not surprised that the professionals at the Library of Congress put us in Z666.5, a category whose components are listed as:

• Bibliography. Library Science. Information Resources
• Libraries Topic Component
• Library science. Information science Topic Component
• Information organization Topic Component
• General works Topic Component

On the other hand, at Amazon.com you find TDO if you search for books on "library management" - and in the Apple IBooks store it is categorized as "System Administration."