FAQ & Resources

General FAQ Technical FAQ Resources


eBook Formats

What is fixed layout?

Fixed-layout EPUB is a very popular format for children's and highly graphical eBooks. Unlike standard eBook files, these eBooks can keep many of the same layout elements and designs as their print book counterparts and retain much of the "look and feel" of the print book reading experience, but can also contain enhancements that make them more interesting and interactive.

What is reflowable layout?

A reflowable eBook format allows text to reflows with a different screen sizes. The reflowable eBook formats are best for novels and books with few illustrations or photographs, where text can reflow according to screen size.

What is EPUB?

EPUB is the most widely adopted eBook format. EPUB is a free and open eBook standard, developed by the International Digital Publishing Forum (IDPF).
The EPUB standard supports both reflowable and fixed layout formats. eBooks in the EPUB format have rapidly gained popularity among major publishers and retailers worldwide. An open-standard format, it provides interoperability between software and hardware for unencrypted reflowable eBooks. EPUB is supported across virtually all eReader platforms except for Amazon Kindle, including the Apple iPad and iPhone, Barnes & Noble, Kobo, Sony and Android devices.

What is Mobi?

Mobi is a proprietary eBook format specific to Amazon-manufactured devices, such as the Kindle, Kindle Fire, or Mobipocket Reader. To distribute eBooks to any Amazon eReading platform, a Mobi version is required.
Mobi eBooks can be viewed on the following devices:

  • Amazon Kindle eInk devices (e.g., Kindle Paperwhite, Kindle Touch, etc.)
  • Kindle Fire/Fire HD tablets
  • Kindle Previewer
  • Kindle Mobile and Desktop Apps (e.g., Kindle for Android, Kindle for PC, Kindle for Mac, etc.)
  • Mobipocket Reader

Mobi supports both fixed layout and reflowable layout. Mobi files are developed as per Amazon's latest specifications.
A more robust version of Mobi is called KF8. KF8 can handle a number of special features, including embedded fonts and HTML5 support.

What is ePib?

ePib is an eBook format developed by Barnes & Noble for their eReaders and tablets, including the Nook and Nook Color. ePib supports only fixed layout format and is best suited for children's eBooks. ePib files are developed per the latest Nook Kids Book Builder specifications.
For information on our quality checks, please see eBook Conversion and Guidelines.

Source Files

What is XML?

XML (Extensible Markup Language) is a device-agnostic markup language that offers publishers enhanced flexibility in repurposing content for print, online, or mobile output. It defines a set of rules for encoding documents to be both human and machine-readable. XML was created to structure, store, and transport information, not to display it. XML tags are user/publisher-defined.
AptaraDirect offers the following widely accepted XML formats:

  • DocBook DTD XML
  • NLM Book DTD XML / NLM Journal DTD XML

What is DocBook DTD XML?

DocBook DTD is a semantic markup language typically used for technical documentation. It describes the meaning of content as opposed to its style or format. DocBook provides a large number of semantic element tags.
For DocBook DTD conversions, files will be developed as per the latest DocBook DTD standards. However, specific versions can be used if customer-specified.

What is NLM Book DTD XML?

NLM Book DTD provides a common platform by which publishers and archives can exchange journal content. NLM DTD provides a set of XML schema modules that define elements and attributes for describing the textual and graphical content of journal articles as well as some non article material such as letters, editorials, and book and product reviews. NLM DTD is very popular with aggregators and libraries.
For NLM Book DTD conversions, files will be developed as per the latest NLM Book DTD/NLM Journal DTD standards. However, different versions can be used as per your requirements.

What is Microsoft Word?

Microsoft Word is a common word-processing program for content authoring. With AptaraDirect, content can be extracted from almost any type of source file and converted into a Word document per customer specifications. Both styled and unstyled Word format conversion is offered.

What is styled Word conversion?

Styled Word documents include content formatting and layout. We extract your content from different supported input files and convert it into Word documents. We also add standard styles in Word documents for better representation of the text.

What guidelines do you follow for styled Word document creation?

If there are no specific instructions from the customer, then Word would be developed as per the print layout. For XML/SGML input, we require PDF for formatting purposes.

What standard quality checks are followed for styled Word documents?

Aptara conducts various quality checks to ensure the highest level of content conversion quality and accuracy.
Our standard quality checks are as follows:

  • Page size: Per the source file
  • Margin of page: Per the source file
  • Fonts: Matched per the source or supplied by the customer
  • Font size: Per the source or specification by customer
  • Line spacing: Per the source or specification by customer
  • Alignment: Per the source file
  • Chapter title, author, and heading level font sizes change per the source file
  • Figure legends, boxes, and tables should be per the source file

What is unstyled Word conversion?

This process allows extraction of content from a non-Word source file and conversion of it into a standard Word document.


What is an ISBN and why I need one?

The International Standard Book Number (ISBN) is a unique numeric commercial book identifier based upon the 9-digit Standard Book Numbering (SBN) code for the bookseller and stationers. The ISBN is 13 digits long if assigned on or after 1 January 2007, and 10 digits long if assigned before 2007. An ISBN is assigned to each edition and variation (except reprinting) of a book, for example an ebook, a paperback, and a hardcover would each have a different ISBN.
Some basic points about ISBNs:

  • A print book ISBN cannot be reused for its eBook component.
  • One unique ISBN can be used per type of book.
  • A type of book is Kindle/mobi/PRC, EPUB (Nook, Apple, etc.), PDF, audio, print, etc.
  • If you are changing your book beyond typos, then you need a new ISBN.
  • You do not need an ISBN to publish your book through Amazon Kindle Direct Publishing (KDP) or Barnes & Noble PubIt (Nook).

How much does an ISBN cost?

You can buy 1 ISBN for $125, 10 ISBNs for $250, 100 ISBNs for $575 and 1000 ISBNs for $1000.

Where I can buy ISBN for my books/ebooks?

Worlddwide, coordinated by the International ISBN Agency in Berlin, Germany. In the United States, ISBNs are assigned by the U.S. ISBN Agency RR Bowker. For more information on ISBNs, please visit www.ISBN.org.
RR Bowker is authorized agent for selling ISBNs in the United States. Please visit www.myidentifiers.com to buy ISBNs for your books/eBooks.

Do I need a new ISBN if I am doing changes in my books/eBook?

No new ISBN is needed if:

  • The changes to your eBook are minor spelling, grammar or typographical corrections.
  • You are changing non-content details about your eBook, such as book pricing, long and short descriptions, genre listings, keywords and any other promotional or sales information.

A new ISBN is needed if:

  • You are implementing any other change to the eBook?s content. This includes, but is not limited to,
    • removing or adding text,
    • changes to the creative team listed in the book,
    • changes to the eBook's title or subtitle,
    • adding or removing illustrations, or
    • or adding or removing audio or video.

Can I use same ISBN no for both Kindle and EPUB, since they?re both ebooks?

No, you need a separate ISBN for each type of book format. Mobi/PRC/Kindle format, EPUB, audio, print, etc. are separate formats and require a different ISBN.