Here is an example from the Cataloging-in-Publication data from the first book I could grab:
Intellectual Property 2. Inellectual property—United States 3. Computer Software—Law and legislation I. Title.
The topics change from book to book, but in every last book I could find with CiP data, the topic list ends with “I. Title”. Why?
It’s clearly out of context at the end of the list of subjects, since the book’s title (I assume that’s what it alludes to) is rarely a subject. Was there ever a context where the “I. Title” part made sense? Are there books that don’t have it, and if every book has it, why is it there?
The Arabic numerals are for the subject headings.
The Roman numerals indicate headings other than the main entry. In most books, the main entry is the author. The title is another. Sometimes an item may not have a title because it doesn’t have a title page.
In other words, were you running a card catalog this would be useful to you. You’ll notice that books with no author or a whole bunch of authors won’t have that, because the title will be the main entry.