Knowledge · Rules
Rules
Understand common EPUB submission issues, why they matter, and whether Cermify can help.
- EPUB standards check results — This result summarizes the official W3C EPUBCheck run on the exact EPUB bytes shown in the report. ERROR/FATAL findings keep Cermify's local…
- Destination-specific legacy markup check — Kindle Format 8 documents support for several deprecated tags, including font, center, big, and strike. Cermify reports marquee as a warning…
- Book navigation is missing or out of sync — Your EPUB's navigation does not give the publishing platform a reliable way to move through the book.…
- A table of contents link does not work — A table-of-contents entry leads to content the publishing platform cannot find.…
- Book details are incomplete — Required book details are missing or incomplete in the EPUB.…
- Reading order is incomplete — The EPUB does not provide a complete, reliable order for reading its content.…
- The EPUB file package is inconsistent — The EPUB's contents and file declarations do not agree, so the publishing platform may not process the book reliably.…
- Content encoding evidence — EPUB permits UTF-16 as well as UTF-8. A valid UTF-16 BOM is a non-actionable warning; invalid byte sequences or replacement-character corrup…
- Book content structure is invalid — Some book content is structured in a way that can prevent reliable rendering or submission.…
- A link target could not be resolved — Cermify could not resolve an inspected local link target in the EPUB package. This file observation does not establish a store importer reje…
- A CSS pattern was observed — This check observes remote stylesheet imports and global justification. KDP documents CSS @import support and justified default text; these …
- A book image is missing — The EPUB refers to an image that is not available as part of the book file.…
- A book font resource is unavailable — The EPUB includes a font resource that the publishing platform may not be able to use reliably.…
- Apple Books EPUB 2 import is unverified — A package version of 2.0 does not by itself prove whether the current Apple Books importer will accept the EPUB. Changing that number alone …
- Apple Books EPUB 3 navigation is missing — An EPUB 3 package needs its declared Navigation Document. EPUB 2 uses NCX; lack of an EPUB 3 nav alone is not an A-NAV finding for EPUB 2.…
- OPF creator metadata is absent — The EPUB package has no dc:creator element. Apple's OPF technical minimum does not list this element, and its absence alone does not establi…
- The book cover is not declared — Apple Books cannot find the cover information it expects in the EPUB.…
- Apple Books script requirements — Apple Books supports JavaScript interactivity under documented restrictions. Cermify reports only statically verifiable violations such as i…
- Embedded media format observation — Apple Books documents supported HTML5 audio and video requirements, including container, codec, and manifest media type. A file extension or…
- Protected content needs manual Apple review — Apple Books documents support for recognized IDPF font obfuscation when it targets an existing manifested font. Other, malformed, unresolved…
- Deprecated HTML element observed — A deprecated HTML element is present. This non-blocking observation does not establish Apple Books rejection; exact EPUB conformance finding…