Is there any reason not to use EPUB after CSS3-break standard is incorporated to browsers?

Or will this not be a barrier?

  • for transform HTML or XHTML into PDF, see print-css.rocks (!) or publishing industry from XSL-FO to CSS3. So, can I assume that we not need PDF as main format, PDF it is only a printer-output mode, the main "open ecosystem format" is HTML+CSS.

  • the renderization-engines: yes, it is a barrier... But they are evolving in the CSS-break standard tests. (eg. Chromium passed in 6 of 8 CSS-break tests)... So we can suppose that in near future (2018 or 2019) good "HTML for print" will arrive.
    In this "imagined context" there are another barrier?

As this comment here, right now, EPUB v3.1+ standard is adopting CSS-break,

The following modules have completed design work, and are fairly stable, but have not received much testing and implementation experience yet. We hope to incorporate them into a future snapshot.

So, this will happen automatically when CSS working group (as 2018... 2019 Snapshot) decides the CSS-break spec is both stable and widely implemented.

NOTE for working definition and scepticisms

Most of EPUB readers produce ugly layout, and EPUB3 format without CSS3-break can't produce good or professional-quality layout as PDF format... So, there are a lot of scepticism about EPUB. Please, lets imagine the future in this question (!), please ignore this kind of scepticism.
CSS3break is to improve EPUB layout, and this question is supposing (is correct?) that PDF layout and EPUB layout will be equivalent when printing.

... And this quesiton is also not concerned with the (supposedly finite) development time in web browsers ... "The future is now!" for investments and plans in digital preservation.

WORKING DEFINITION: the context here is the use of HTML5+CSS3break and/or EPUB for official documents, in a digital preservation perspective. Examples:

  • Open structure and semantic: HTML5 offers a lot of tags for organize contents in a structured way and some semantics. Adding RDFa layer (with good standards as SchemaOrg) we can express any kind of semantic for official contents, from scientific articles (ScholarlyArticle) to contracts and legislation.
    In November 2017 ~1,229,000,000 of URLs was using some kind of HTML+semantic, mainly Microdata and some other variants of the RDFa standard. Digital content ecosystem need HTML, CSS, RDFa, MathML, etc. (not PDF).
    When a digital preservation initiative need to "zip all content in to a file", can use EPUB standard.
    Conclusion: only attractives (plans to enhance all with CSS3-break), no barriers to use EPUB for digital preservation.

  • Open Science: today they use a XHTML-like format, the JATS standard, as official digital preservation format for scientific articles, and the "content matrix" that generats all other formats (EPUB and HTML automatic but PDF not)... There are many "official preservarion repositories" as PMC and SciELO. PubMed Central offerts ~5 million articles in all formats, including ~5 million of EPUB.
    Sample PMC2150930 article in all formats: ugly layout EPub and good PDF, and HTML variants as HTML classic layout, HTML modern layout.
    There are plans to migrate from JATS to ScholarlyArticle in minor publisher houses, to use directly HTML5+RDFa as official digital preservation format.
    Conclusion: only attractives, no barriers to use EPUB+CSS3break for digital preservation in open science.

  • Open Government and Digital transparency: today all contries are migrating its "official documents", that are articles in the government gazettes, from PDF to HTML and/or EPUB... They are going up the stairs in the 5-star deployment scheme for Open Data. It is a transition: e.g. European countries National Law, Brazilian Official Gazzete, UK legislation, etc. today are producing "twin documents" (HTML and PDF) from a XML matrix.
    ... With CSS3break they will need only HTML as matrix. In fact, there are plans to migrate from "ugly non-standard XML" to good XHTML5 (plus RDFa when necessary) in minor publisher houses, so HTML ecosystem as "content matrix", and EPUB as official digital preservation format.
    Conclusion: only attractives, no barriers to use EPUB+CSS3break for digital preservation in open government.

PS: of course, the conclusions above are personal and only a illustrative sample. The question is looking for better foundations, credible and/or official sources, etc.

  • I need answer for +50 rep. Jun 15, 2018 at 3:11
  • @Peter Krauss: I don't understand what your actual question is. Is it about epub books or pdf books? If it's about epubs, the introduction of new CSS selectors doesn't matter because epubs aren't rendered by web browsers. If it's about HMTL-to-PDF conversion, it also doesn't matter, since many HTML-to-PDF converters, e.g. Prince, support only a subset of CSS selectors. And finally, it takes forever until web browser developers add support for new CSS selectors. I.e., it's a purely academic question.
    – user4665
    Jun 15, 2018 at 7:56
  • Hi @NemoXXX, yes, the question seems, but it is not "purely academic question" as you say. The business face is investment, the "how much" and the "timming" thing... Raising capital for a small publishing houses: we need discuss, with a little bit more of "reliable theoretical fundations", to reduce risks and attrack more investors. Jun 15, 2018 at 15:36
  • @Peter Krauss: It'd help if you defined your role. Are you a publisher or do you plan to develop and/or sell software products that'll generate epubs and pdf files? BTW, the epub 3.1 standard is pretty much dead, because nobody bothered to develop a reference application and epub3.2 doesn't look much better. For more information see Why Specs Change.
    – user4665
    Jun 15, 2018 at 17:01
  • Thanks @misdeed (!), please check if you agree with the question's text changes. Jun 15, 2018 at 23:34

1 Answer 1


First, the Calibre epub reader does include a function to allow you to print an epub file. It accomplishes this by converting it first to a PDF.

There have been efforts to add new features in CSS to make it easier to print (and as a replacement for FOP).

It's already fairly easy to produce both EPUB and PDF. If that is true, there is no special need to make EPUB printable.

The end goal of EPUB is not to produce printable documents, but it's probably true that certain publishers prefer PDF because people can easily download it and print it -- and that feature in missing in EPUB readers. Government bodies, open source communities, educational institutions and businesses probably benefit from letting users print EPUB files. But Adobe Digital Editions does not include the print function for an unencrypted epub file.

Up until now, book publishers have been the main force behind the EPUB working group, and so the print-function has been a low priority. (They don't even want epub reading systems to allow cutting and pasting!) I've seen commentary predicting that the epub group will align itself more closely to the HTML5 standards group, so maybe it will be easier to incorporating the increasing print functionality of CSS.

Currently it is not hard to convert EPUB into the more easily printable PDF. Even Calibre does it relatively easy or well, Adobe Indesign should make such conversions easy to do as well. Incorporating this function into the EPUB reader does not strike me as particularly hard, except Adobe has no commercial incentive to do so.

Another issue is Google. The Google Play epub reader doesn't support page-oriented css (like page-break-before, etc). THE GP reader (and even Readium) don't have print capability even for unencrypted epubs or PDFs. When viewing PDFs in Google Play books on a web browser, you can't even print that. You must open the PDF in the browser itself.

I would guess that scientific publishers like Elsevier have perfected the PDF production process and don't see any real advantage in focusing more on EPUBs -- especially when it's already easy to produce output in both EPUB and PDF (and mobi, etc). With articles and journals, they want to prevent people from printing these things (or at least to control this ability), and Adobe Reader offers these controls already on PDF. Therefore, there's no need for publishers to want a change.

Until an epub reading system (standalone or browser-based) develops a way to allow the publisher to control what printing is allowed and what printed is not allowed, it seems unlikely that printing epubs will ever be urgent for people who build reading systems.

From my standpoint as a small indie publisher, I could care less about whether my unencrypted ebooks are easy to print. If an ebook is unencrypted, then anyone could unzip the file and paste what they want into a MS word document or use Calibre to do it. I see no reason to change my formatting to accommodate the possibility of printing. (Of course, my ebooks are not particularly technical or require elaborate formatting). Maybe my viewpoint will change later.

  • Hi, thanks! About your comment "There have been efforts to add new features in CSS to make it easier to print", I understand that it is 100% the w3.org/TR/css-break ...So, in the context of the question, it is important to explicit that you agree about this consideration, or not. Jun 21, 2018 at 12:24
  • I don't have any special knowledge about this subject, but in the HTML world, this is certainly happening. In the ebook world, it's hard to say... Jun 22, 2018 at 14:20

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