Answers.Body: <p>The IDPF states the following in a <a href="http://idpf.org/forum/topic-623">thread</a> about <strong>EPUB 3 Rendering in EPUB 2 reading systems</strong></p>
  
  <blockquote>
    <p>Although EPUB 3 is not perfectly backwards compatible with EPUB 2, a goal of the recent revision was to ensure, as much as possible, a basic level of rendering when features overlap.</p>
  </blockquote>
  
  <p>The thread particularly mentions that providing the NCX data is necessary, which has been superseded with <a href="http://www.idpf.org/epub/30/spec/epub30-contentdocs.html#sec-xhtml-nav">EPUB Navigation Documents</a>
  as described in the <a href="http://www.idpf.org/epub/30/spec/epub30-changes.html#sec-deprecations-ncx">EPUB 3 changes document</a></p>
  
  <p>So, if some care is taken, EPUB 3 files can be made to render on EPUB 2 reading systems.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2013-12-20T16:16:36.827Z
Answers.LastActivityDate: 2013-12-20T16:16:36.827Z
Answers.UserDisplayName: Anthon
Answers.Body: <p>Your best bet is to ask before you buy.  </p>
  
  <p>It depends on the reason the book was released in the EPUB 3 format. If it's a static text, and the publisher was only trying to follow the latest guidelines and standards, they may have added the extra bits required by the older standard, so it would degrade gracefully and be available to more customers.</p>
  
  <p>If, on the other hand, the book was released as an EPUB 3 in order to take full advantage of the standard's dynamics and interactivity, it's likely that the publisher didn't add the required legacy information.  They might have pegged a particular device, to ensure that the book would function predictably.  For example, Walrus Books released H.P. Lovecraft's novel, "Kadath", for the iBooks app in EPUB 3.  It is highly interactive and intended for the iPad. They had no reason to make it work on other devices, and probably didn't bother with legacy shims.</p>
  
  <p>Regarding your question about software, I'm not aware of a good GUI for creating EPUB 3s. I use Dreamweaver to modify the HTML, CSS, and JavaScript code directly, and ePubPack and 7zip to pack and unpack it.  Then I test it with ePubCheck. </p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2013-12-22T04:42:26.563Z
Answers.LastActivityDate: 2013-12-22T04:49:23.010Z
Answers.LastEditDate: 2013-12-22T04:49:23.010Z
Answers.UserDisplayName: Eclectic
Answers.Body: <p>I just wanted to add that Nook is able to display epub3 files (without supporting a lot of its features) and Kindle Previewer (the tool that converts epub to kindle format) will accept epub3 files for conversion. Again, the latest Kindle devices don't support a lot of optional epub3 features, but it can still display it. Same for ibooks.</p>
  
  <p>Smashwords is iffier (although I haven't checked recently). A year ago I noticed that they were using an outdated version of epubcheck which flagged as errors any epub3 file. I noticed this first in 2012, noticed that it still had not been fixed by Smashwords as of Oct 2013, so it may have been fixed by now. [2017 Update: Smashwords has fixed this]. </p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-02-24T19:02:36.180Z
Answers.Text: You have provided the same answer for two separate questions (http://ebooks.stackexchange.com/questions/974/testing-a-readers-epub-3-0-support/990#990). This is generally frowned upon. From what I can tell the first part of your answer fits this question and the second part fits the other answer. Please consider revising your answers or removing one of the answers (you could leave a comment that links to the other answer).
Answers.UserDisplayName: Jason Down
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-02-24T18:51:36.987Z
Answers.LastActivityDate: 2017-04-17T16:57:20.637Z
Answers.LastEditDate: 2017-04-17T16:57:20.637Z
Answers.UserDisplayName: idiotprogrammer
Body: <p><a href="https://ebooks.stackexchange.com/questions/59/what-are-the-differences-between-epub2-and-epub3">This prior question</a> is about the differences between EPUB 2 and EPUB 3.</p>
  
  <p>What is more interesting to me, as an owner of three different EPUB 2 devices, is: can EPUB 3 files, and particularly the book text parts, be rendered on a EPUB 2 reading systems (of course dispensing with EPUB 3 specific features)?</p>
  
  <p>Can all such files be rendered, or do they need special setup? Assuming compatibility is possible, is there software already supporting generation of such EPUB 3 files compatible with EPUB 2 reading systems?</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2013-12-20T22:39:11.107Z
Comments.Text: While it is not practical in many cases, the epub documents can be manually edited to remove any epub3 specific functionality. I've been forced to do something similar where I had to remove javascript code that only worked on a Kobo Reader. On my Sony Reader, the epub would not render properly (very large text where a single word would take up the entire screen).
Comments.UserDisplayName: Jason Down
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2013-12-21T05:31:50.427Z
Comments.Text: @JasonDown I know about changing EPUBs manually, but did not think about doing that for this purpose. I was more looking at buying an EPUB 3 book file and it being usable at is. But thanks for the suggestion!
Comments.UserDisplayName: Anthon
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2013-12-22T13:43:31.830Z
Comments.Text: You are asking two questions here. The last sentence should be a separate question
Comments.UserDisplayName: mmmmmm
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2013-12-23T13:46:02.570Z
Comments.Text: @Anthon. No problem. I learned quite a lot about epub files by opening them up and playing around with them.
Comments.UserDisplayName: Jason Down
Tags: <ebook-readers><epub>
Title: Can EPUB 3.0 be viewed on EPUB 2 devices
UserDisplayName: Anthon
ThreadText: # Can EPUB 3.0 be viewed on EPUB 2 devices
  
  (Asked by: username_0 on 2013-12-20)
  
  [This prior question](https://ebooks.stackexchange.com/questions/59/what-are-the-differences-between-epub2-and-epub3) is about the differences between EPUB 2 and EPUB 3.
  
  What is more interesting to me, as an owner of three different EPUB 2 devices, is: can EPUB 3 files, and particularly the book text parts, be rendered on a EPUB 2 reading systems (of course dispensing with EPUB 3 specific features)?
  
  Can all such files be rendered, or do they need special setup? Assuming compatibility is possible, is there software already supporting generation of such EPUB 3 files compatible with EPUB 2 reading systems?
  
  **Tags:** ebook-readers, epub
  
  > **Comments:**
  > **username_1**: While it is not practical in many cases, the epub documents can be manually edited to remove any epub3 specific functionality. I've been forced to do something similar where I had to remove javascript code that only worked on a Kobo Reader. On my Sony Reader, the epub would not render properly (very large text where a single word would take up the entire screen).  
  > **username_0**: @JasonDown I know about changing EPUBs manually, but did not think about doing that for this purpose. I was more looking at buying an EPUB 3 book file and it being usable at is. But thanks for the suggestion!  
  > **username_2**: You are asking two questions here. The last sentence should be a separate question  
  > **username_1**: @username_0. No problem. I learned quite a lot about epub files by opening them up and playing around with them.  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_0 on 2013-12-20. Score: 18
  
  The IDPF states the following in a [thread](http://idpf.org/forum/topic-623) about **EPUB 3 Rendering in EPUB 2 reading systems**
  
  > Although EPUB 3 is not perfectly backwards compatible with EPUB 2, a goal of the recent revision was to ensure, as much as possible, a basic level of rendering when features overlap.
  
  The thread particularly mentions that providing the NCX data is necessary, which has been superseded with [EPUB Navigation Documents](http://www.idpf.org/epub/30/spec/epub30-contentdocs.html#sec-xhtml-nav)
  as described in the [EPUB 3 changes document](http://www.idpf.org/epub/30/spec/epub30-changes.html#sec-deprecations-ncx)
  
  So, if some care is taken, EPUB 3 files can be made to render on EPUB 2 reading systems.
  
  
  ---
  
  ### Answer by username_3 on 2013-12-22. Score: 6
  
  Your best bet is to ask before you buy.
  
  It depends on the reason the book was released in the EPUB 3 format. If it's a static text, and the publisher was only trying to follow the latest guidelines and standards, they may have added the extra bits required by the older standard, so it would degrade gracefully and be available to more customers.
  
  If, on the other hand, the book was released as an EPUB 3 in order to take full advantage of the standard's dynamics and interactivity, it's likely that the publisher didn't add the required legacy information. They might have pegged a particular device, to ensure that the book would function predictably. For example, Walrus Books released H.P. Lovecraft's novel, "Kadath", for the iBooks app in EPUB 3. It is highly interactive and intended for the iPad. They had no reason to make it work on other devices, and probably didn't bother with legacy shims.
  
  Regarding your question about software, I'm not aware of a good GUI for creating EPUB 3s. I use Dreamweaver to modify the HTML, CSS, and JavaScript code directly, and ePubPack and 7zip to pack and unpack it. Then I test it with ePubCheck.
  
  
  ---
  
  ### Answer by username_4 on 2014-02-24. Score: 1
  
  I just wanted to add that Nook is able to display epub3 files (without supporting a lot of its features) and Kindle Previewer (the tool that converts epub to kindle format) will accept epub3 files for conversion. Again, the latest Kindle devices don't support a lot of optional epub3 features, but it can still display it. Same for ibooks.
  
  Smashwords is iffier (although I haven't checked recently). A year ago I noticed that they were using an outdated version of epubcheck which flagged as errors any epub3 file. I noticed this first in 2012, noticed that it still had not been fixed by Smashwords as of Oct 2013, so it may have been fixed by now. [2017 Update: Smashwords has fixed this].
  
  > **Comments:**
  > **username_1**: You have provided the same answer for two separate questions (http://ebooks.stackexchange.com/questions/974/testing-a-readers-epub-3-0-support/990#990). This is generally frowned upon. From what I can tell the first part of your answer fits this question and the second part fits the other answer. Please consider revising your answers or removing one of the answers (you could leave a comment that links to the other answer).  
  
  ---
  
  