What subject codes do
Subject codes give distributors, retailers, libraries, and data partners a structured way to categorize a book. They are not the same as free-form keywords, and they should reflect the book’s actual content.
BISAC in practice
BISAC subject headings are widely used in the United States and Canada. Publishers typically choose the most specific appropriate headings rather than selecting broad categories simply because they seem popular.
Thema in practice
Thema is designed for international use and supports qualifiers that can refine subject meaning by place, time period, educational purpose, interest level, and other dimensions.
Do you need both?
That depends on the distribution chain. Some partners map one scheme to another; others request a particular system. Keep a master metadata record so classification choices stay deliberate and consistent.
Primary sources
- BISG BISAC — BISAC subject headings information
- EDItEUR Thema — international Thema subject classification