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Glossary

What is the EPUB spine?

Updated:

The spine is the ordered list, inside the OPF package document, of the content documents a reader pages through from start to end. It sets the default reading order of the book.

Why it matters when you convert a PDF to EPUB

When EPUBLab turns a PDF into an EPUB, chapters detected from the PDF's outline or heading sizes become separate documents, and their order in the spine is the order you read them. The spine must contain at least one linear item, and each manifest item may appear in it only once.

Items marked linear="no" are skipped when paging through, so they must be reachable from a link. The spine also carries page-progression-direction for right-to-left books.

Related terms

EPUBCheck messages about this

  • OPF-033 The spine contains no linear resources.
  • OPF-034 The spine contains multiple references to the manifest item with id "…".
  • OPF-096 Non-linear content must be reachable, but found no hyperlink to "…".
  • RSC-011 Found a reference to a resource that is not a spine item.
  • OPF-001 There was an error when parsing the EPUB version: ….
  • OPF-002 The OPF file "…" was not found in the EPUB.
  • OPF-003 Item "…" exists in the EPUB, but is not declared in the OPF manifest.
  • OPF-004 Invalid prefix declaration: leading or trailing whitespace is not allowed.
  • OPF-004a Invalid prefix declaration: found empty prefix.
  • OPF-004b Invalid prefix "…": must be a valid non-colonized name (aka "NCName").

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FAQ

What is the EPUB spine?

The spine is the ordered list, inside the OPF package document, of the content documents a reader pages through from start to end. It sets the default reading order of the book.