Category Archives: Tech Tips

Reminder About EPUB Validation

Publishers that are providing distribution-ready files should make sure the ePubs validate and are free of errors before sending them to NBN. The latest ePub standard is 4.0.1, but some vendors are still using 3.0.1 to validate files and will reject files that don’t validate to that version. To check ePubs that are less than 10MB, you can use this IDPF validator. Common validation warnings and errors are below:

WARNING: Filenames contains spaces. Consider changing filenames such that URI escaping is not necessary
SOLUTION: Remove the spaces from the files names of the .html and .jpg files inside the ePub.
EPUBCHECK VERSION: 3.0.0, 3.0.1, 4.0.1

ERROR: element “font” not allowed anywhere; expected the element end-tag, text or element “a”, “abbr”, “acronym”, “applet”, “b”, “bdo”, “big”, “br”, “cite”, “code”, “del”, “dfn”, “em”, “i”, “iframe”, “img”, “ins”, “kbd”, “map”, “noscript”, “ns:svg”, “object”, “q”, “samp”, “script”, “small”, “span”, “strong”, “sub”, “sup”, “tt” or “var” (with xmlns:ns=”“)
SOLUTION: Instead of using a font tag, set the font size in the CSS stylesheet using the font-size property, and then apply that style to the line or paragraph that had the font tag.
EPUBCHECK VERSION: 3.0.0, 3.0.1, 4.0.1

ERROR: Non-standard stylesheet resource ‘OEBPS/page-template.xpgt’ of type ‘application/adobe-page-template+xml’. A fallback must be specified.
SOLUTION: Remove the reference to the page-template stylesheet.
EPUBCHECK VERSION: 3.0.1; This error is due to a glitch in epubcheck 3.0.1 but some vendors are still using that version, so files with this error won’t go up on those sites.

ERROR: OEBPS/Fonts/Fontname: referenced resource missing in the package (or /OEBPS/template.css: Referenced resource could not be found in the EPUB.)
SOLUTION: The font file is missing from within the ePub, In most cases, you can simply remove the src=”…” text from the place of reference since the ePub isn’t loading the font anyway.
EPUBCHECK VERSION: 3.0.0, 3.0.1, 4.0.1

ERROR: Referenced resource could not be found in the EPUB.
SOLUTION: A link or reference is made to content not provided within the ePub. This can be caused by several things including: 1. an improperly embedded font, 2. missing image file, or 3. incorrectly written hyperlink to a web address. Add the missing content or remove the reference.
EPUBCHECK VERSION: 3.0.0, 3.0.1, 4.0.1

ERROR: File name contains the following non-ascii characters: […]. Consider changing the filename.
SOLUTION: Change the file name of the image or html file that so that it contains only US keyboard characters.
EPUBCHECK VERSION: 3.0.0, 3.0.1, 4.0.1

If you have any questions about if your eBooks have validation errors, your Fusion representative will be glad to help.



Filed under ePUB creation, File creation, Submission Requirements, Tech Tips, Uncategorized

Price Promotions

If you want to run a price promotion for a title that is currently distributing, please give your Fusion rep as much advanced notice as possible. Amazon requires at least six weeks advance notice for a price promotion. Most of the other big vendor sites don’t require quite as much advance notice, but we ask that you use Amazon’s time-frame for any future price promotions.

If you have questions or this is a feature you are interested in, please contact your Fusion rep.

If you are interested in promotions such as Amazon Daily Deals and B&N Free Fridays, please contact Jason Brockwell at

*Please note that once we request the price promotion, it is then up to the individual vendor sites to run the promotion.

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Tech Tips: Images, InDesign, and ePub

Object Export Options…

After setting an image in InDesign, select the image with the selection tool. At the top of the screen, click Object, and then select Object Export Options… and you’ll get the following dialogue box:

object export options

In this dialogue box, you can adjust the export options of that particular image/object when exporting to epub. You can adjust the output resolution, quality, and format. Here, you can also set your images to adjust their size “Relative to Page Width” which means that the image size will adjust to the width of any device and the different orientations of that device. Additionally, you can set the output alignment and spacing.

If you have numerous images that will all have the same export options, the same settings from the Object Export Options… dialogue box are available in the epub export settings. Those settings, however, will apply to all of the images though you can choose to not override local object export settings.

Anchoring Images

When exporting to epub, InDesign “reads” your document left-to-right, top-to-bottom and arranges the text and objects in the order in which it encounters them. This can cause some objects to appear in unexpected locations. If your text is all in one thread, when exporting to epub, InDesign will put all of your text first, then all of your images and other objects will fall to the end of the text.

To prevent this, you must to anchor your images and any other objects (tables, textboxes, sidebars, etc.). All you have to do is: select your image/object, click the blue square in the top right corner of the object, and drag it until the cursor is in the location you’d like the object to appear in the epub as shown below.

anchor before

After anchored, the object will have an actual anchor where the blue box used to be.

anchor after

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Tech Tips: InDesign Basics for ePub

The following are good habits that you should apply to your InDesign files in order to produce good ePubs. I’ve also noted the reasoning behind each step as it relates to ePub creation.

Separate Files

Set all sections of your book in separate files, including the title and copyright pages. Then, create a book file (File > New > Book) and add your InDesign Files to the book file. When exporting to ePub, the separate InDesign files will each become a separate html file. If you set your book in one InDesign file, then when you export to ePub, your ePub file will only contain one html file and, therefore, all of the sections of the book will run together, with no separation.

File Info…
Open the first file in your book. Go to File > File Info… and fill in the Document Title and Author fields. The title and author information will be added to the ePub’s metadata in the content.opf file. Without this information in the content.opf file, when viewing your epub, the reader will display “Unknown” instead of the title or author.

Style Everything!
Create and apply paragraph and character styles for all variations of formatted text. When exporting to ePub, your styles will become the basis for the stylesheets file in the ePub. If you format all of your text by hand, not using styles, then when exporting to ePub, the stylesheets file will be full of generically named styles, which makes it difficult to make adjustments to your ePub after it’s been created. This also applies to objects and tables, so be sure to use Table and Cell styles as well as Object styles.

TOC Styles
Again, in the first file in your book, go to Layout > Table of Contents Styles… and click “New…” Find your chapter title paragraph style, select it, and click “<<Add”. Click “Include Book Documents” at the bottom of the window and click OK. The newly created TOC style will be used to generate the toc.ncx file in the ePub, which displays the navigation table of contents in the e-reader.

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A Quick Note About Free ePub Converters

Beware of free ePub converters that you find on the web! The Fusion team here has received ePub files from various publishers over the recent months that were created with one free ePub converter program or another. As alluring as a free ePub conversion can be, they are fraught with failing errors.

If you choose to test one of these free converters out, check over the final ePub before sending it to your Fusion contact. Also, please confirm that the file validates. One site that will confirm that your ePub validates is:

The ePub must be 10MB or less for this validator.

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Apple Rejections

Apple is the pickiest vendor that we supply to and currently the only vendor that reviews titles before making them for sale. The Apple review team rejects titles for a variety of reasons, but Apple has not released a guide that details what the QA team looks for. However, the following is a break-down of the most common rejections we see:

    • Spaces in the .xhtml file names
        • The ePUB will fail to distribute to Apple if there are spaces in the file names. The error message that Apple gives is “illegal character in path at index…”


    • Small front cover
        • If the front cover JPG is too small, the title will fail to distribute to Apple. The front cover JPG must be at least 1400 on the short side side.


    • EPUB contains images of more than 4 million pixels
        • 2 million pixels equates to approximately 1000×2000. Usually the image in question is a front cover image but can be scanned text or other art in the ePub. Sometimes we receive rejections with the rejected images specified.


    • Prices in the EPUB (including ads and back covers)
    • Inaccurate/Incomplete Table of Contents
        • This refers to the auto-generated ToC that customers use to navigate on the devices. If your title is short and does not have sections, be sure to capture front and back matter in the ToC.


    • Blurry/Pixilated images or Illegible diagrams/charts/tables
        • This is often a problem when the diagrams/charts/tables are scanned in and the text is small.
        • Apple may still reject a title if an image appears clear when viewed in normal screen size but is blurry when zoomed in.
        • Image resolution is downgraded as a result of the conversion process, and the conversion vendor we work with does not improve image quality during conversions. To avoid this issue, images, charts, etc. should be high resolution in the PDF sent for conversion.


    • Too much scanned in text (such as whole sections)
    • Overlapping text or Text/images cut off
    • Too much interactivity (e.g. having exercises like a workbook)
    • Cover art/EPUB promises content not included (e.g. a CD/DVD)
  • Cover art not matching title page (different author name, subtitle, etc)

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Adobe Digital Editions

Adobe Digital Editions is a free software application that allows you to view epub files on your computer. However, please note that there are limitations of this program.

  • Certain complex characters do not display in Digital Editions. They can appear as question marks or empty boxes, making it look like there is an error in the epub file when there is no error in the file. This is true not only of unsupported font types in English, but also unsupported foreign languages.
  • Spacing can be an issue. Occasionally, there looks like extra spacing between paragraphs, when no such spacing exists.
  • When looking at a fixed layout epub, the embedded text appears as a separate screen and the lettering is unreadably small. Rest assured that this small text does not show up on the ipad.
  • Depending on the screen size, images and tables can appear cut off.
  • Digital Editions has numbers that look like page numbers. The numbers that appear to the right of the page are just reference numbers for the epub creators. The numbers at the top (that appear like: 10/300) do not actually correspond to the print book and do not correspond to what the customer is seeing on his/her device.

It’s important to remember that looking at an epub in Digital Editions is not how the file will look on an e-reading device. Using Adobe Digital Editions to look at an epub file is an easy and convenient option, but it is always best to view the file on an actual e-reading device to get the customer experience.

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