Why an ebook is not a smaller print PDF
A print interior resolves every line onto a fixed physical page. A reflowable EPUB packages structured documents, resources, metadata, navigation, and styles that a reading system composes for a particular screen and reader preference. Font size can change. Margins can change. A phone can become a tablet. A sighted user can switch themes, while an assistive-technology user may navigate by headings or listen to the same structure. The source must survive all of those interpretations.
That is why visual similarity to print is the wrong primary test. The ebook should preserve hierarchy, emphasis, reading order, navigation, and intentional breaks while allowing the reading system to do its job. Excessively rigid CSS may make one screenshot look controlled and make the actual book fail at large text or on a different engine. Good ebook production is structured restraint.
Conformance, accessibility, and rendering are separate checks
EPUBCheck evaluates the package against the specification and catches many broken references, invalid declarations, and markup errors. That is essential, but a clean result does not tell you whether alternative text is useful, headings describe the document, link labels make sense, or a 200% font setting creates an unreadable layout. Accessibility requirements add semantic and descriptive expectations. Device QA adds the behavior of actual reading systems.
Treat the three layers as complementary. First, eliminate conformance errors and review every warning. Second, inspect structure and accessibility with human judgment and appropriate tools. Third, read representative chapters in more than one engine, at more than one viewport and font size. Finally, inspect the retailer’s ingested preview because the distribution system may transform the source EPUB before a customer receives it.
One manuscript source, two deliberately different outputs
Print and ebook editions should share content truth without sharing layout assumptions. A print blank page may have no role in the EPUB. A running head disappears. A page-number cross-reference may need different wording. A decorative image might remain decorative, while an informative figure needs an alternative. If the author maintains unrelated print and ebook masters, a late correction can reach one format and miss the other.
Cambric’s value proposition is one structured manuscript that can produce fixed print pages and a reflowable EPUB. That does not remove format-specific QA; it makes the source of the two outputs coherent. Correct the manuscript or structure once, regenerate both artifacts, then apply the appropriate preflight to each. The result is a controlled divergence rather than two books drifting independently.
What the matrix proves—and what it refuses to claim
The matrix is grounded in the W3C EPUB 3.3 and EPUB Accessibility specifications and the EPUBCheck project. It is a maintained interpretation of the work a publisher should perform, not a certification service. No row claims that Cambric automatically satisfies every accessibility criterion, every retailer extension, or every unusual manuscript. Those claims would require versioned output specimens and reproducible test reports.
That boundary is useful to buyers. It distinguishes an honest production tool from a promise that collapses a complex release process into one button. Cambric exports EPUB 3 and lets the author maintain the source; the publisher still validates and inspects the released artifact. Our next evidence milestone is a downloadable, versioned sample EPUB with its EPUBCheck report, not a broader adjective in marketing copy.