ONIX 3.0, Thema, BISAC, and BIC: The Metadata Codes That Get Your Book Found

Most indie authors treat metadata as an afterthought. You type in a title, paste a description, and move on. That’s a mistake. Metadata is how retailers and librarians decide where to shelve your book—and whether to shelve it at all.

If you want library distribution, proper categorization, and discoverability across platforms, you need to understand how ONIX 3.0, Thema, BISAC, and BIC work together.

What is ONIX 3.0?

ONIX is the global standard for communicating book metadata between publishers, retailers, and distributors. Think of it as a universal data sheet that carries every detail about your book—from title and author to pricing, format, and subject classification.

ONIX 3.0 is the latest version of this standard. It was specifically updated to handle:

Enhanced discoverability through richer subject classifications
Digital formats including DRM and licensing models
Library-specific fields like borrowing models and acquisition dates
Pre-publication data for pre-orders and upcoming releases

Why does this matter for indie authors? Because if you’re submitting to library aggregators (like Ingram’s LibrarySelector, OverDrive, or Bibliotheca), they expect ONIX 3.0 formatted data. A poorly structured ONIX file means your book might get rejected from library catalogs entirely.

Key ONIX 3.0 Elements for Indie Publishers:

: Your ISBN or proprietary ID
: All physical and digital specifications
: Your cover image, excerpt, and author bio
: The classification codes we’ll discuss next

Subject Classification Systems: Thema, BISAC, and BIC

ONIX carries your data, but it needs classification codes to tell systems what your book is. Three major systems exist, and most platforms require at least one.

BISAC (Book Industry Study Group)

Used primarily in: United States, Canada, and increasingly global English-language retailers.

BISAC codes are single-level hierarchical codes. They’re simple: Fiction > Thrillers > Espionage. The structure is broad-to-specific.

Example BISAC Code: FIC022000 breaks down as:

FIC = Fiction
022 = Thrillers
000 = General

Amazon, Kobo, and most US retailers require BISAC codes. If you’re selling on Amazon US, you must select a BISAC category.

Limitation: BISAC is primarily for retail placement. Libraries often find it too broad for accurate shelving.

BIC (Book Industry Communication)

Used primarily in: United Kingdom, Australia, and parts of Europe.

BIC uses a similar hierarchical structure to BISAC but is the standard for the UK book trade. You’ll encounter BIC codes if you’re distributing to Waterstones, Foyles, or UK library systems.

Example BIC Code: Y indicates a young reader’s book, with further subdivisions for age ranges and genres.

Thema (EDItEUR)

The global standard for the future.

Thema is a multilingual classification system developed by EDItEUR (the international group coordinating book trade standards). It’s designed to work globally, with official translations in over 30 languages.

Why Thema matters:

Multilingual: Classification descriptions appear in the reader’s language
Detailed: Offers more granular categories than BISAC
Library-friendly: Designed to satisfy both retail and academic/library needs
Growing adoption: Barnes & Noble, Nook, and international distributors are moving toward Thema

Example Thema Code: YFM denotes “Children’s / Teenage: Nature and animal stories (Children’s / Teenage)” with further qualifiers available.

How to Assign Subject Codes Correctly

Most authors make one of two mistakes: being too broad or being too specific.

The “Too Broad” Mistake

Choosing Fiction > General or leaving the subject field blank. This kills discoverability. Libraries and algorithms can’t recommend your book if they don’t know what it is.

The “Too Specific” Mistake

Creating a category that doesn’t exist in the official taxonomy. For example, labeling a book “Existential Cyberpunk Thriller” when BISAC only recognizes “Science Fiction > Cyberpunk” or “Thrillers > Science Fiction.”

The Correct Approach

Use multiple codes: Assign 3-5 relevant codes if the platform allows. Your primary category gets retail placement; secondary codes help with cross-recommendations.
Match platform requirements: Retailers like Amazon need BISAC; libraries may need Thema or BIC.
Be honest: Don’t put your thriller in “Romance” hoping for more sales. Algorithms penalize mismatches.
Check official lists: Use the official BISAC Subject Headings List and Thema Classification tables to find valid codes.

The Practical Workflow for Indie Authors

Here’s how to handle metadata for maximum distribution:

Step 1: Get Your ISBNs

Each format (eBook, paperback, hardcover, audiobook) needs its own ISBN. Don’t reuse one ISBN across formats.

Step 2: Create Your ONIX Record

Use a free tool like:

Bowker’s ONIX Generator (for US authors)
Edifact Composer (for more control)
Your distributor’s metadata entry system

Step 3: Assign Codes

Platform	Recommended Code System
Amazon US	BISAC
Amazon UK	BIC or Thema
Libraries (US)	Thema preferred, BISAC acceptable
Libraries (UK/EU)	Thema mandatory
Kobo/Nook	Thema
IngramSpark	BISAC and Thema

Step 4: Validate Your Data

Before submitting:

Verify ISBN formats are correct (ISBN-13, no hyphens in some systems)
Ensure subject codes exist in the official lists
Check that your BISAC codes match your book’s actual content
Confirm your descriptive text doesn’t contain markdown or HTML

Common Questions

Do I need all three systems?

No. Most indie authors succeed with BISAC for retail and Thema for library distribution. If you’re UK-focused, prioritize BIC and Thema. The key is matching the code system to the sales channel.

Can I change codes later?

Yes, but with consequences. Changing your primary BISAC category on Amazon moves your book to a different shelf, potentially affecting rank and visibility. Library catalogs can update records, but it takes time.

What’s the difference between BISAC and Thema granularity?

Thema offers more specific categories in some areas. For example, Thema has dedicated codes for “Philosophical Fiction” and “Cozy Mystery,” while BISAC may only have broader buckets. This granularity helps readers find niche books.

Conclusion

Metadata isn’t glamorous, but it’s the infrastructure of book discovery. ONIX 3.0 is the delivery truck; BISAC, BIC, and Thema are the address labels. Get them wrong, and your book becomes undeliverable.

Take 30 minutes to research the correct BISAC and Thema codes for your book before you hit publish. That small investment determines whether your book gets found—or disappears into the void.