There are a multitude of eReader software products, ranging from open source to proprietary. PeBL is designed to integrate with ePub3 compliant eReaders. For a detailed breakdown of which extensions work in which eReader, refer to the eReader compatibility chart. If you have questions about an eReader not listed on the chart, please contact the PeBL team and we will add it. For the best user experience, we recommend targeting as few eReaders as possible when designing enhanced content. While the core requirement for a PeBL eReader is that it support EPUB 3, it is possible that there may be incompatibilities between some EPUB 3 readers and some PeBL extensions based on decisions made by the eReader developer.
As explained in the 2. Architecture of the platform section of the specification, the PeBL platform is built on the principle of embedding as much functionality as possible inside the books rather than the eReader, to achieve "code portability" and to lessen dependence on eReader software. This mitigates as much as possible issues stemming from these incompatibilities, but it does not eliminate them. See the Compatibility section of the specification for information on reader support for specific extensions.
Guidance for end users (if needed) should be provided by the eReader software. Because PeBL is based on standard eBook technology (EPUB 3 eBooks), the eReader interface should be familiar to end users who are already consumers of eBooks. However, help documentation may need to be included for individual PeBL extensions.
Like most other eBooks, PeBL is designed for tablet computers, but is also usable on the desktop via a desktop eReader. It is, of course, possible to read PeBL books on smartphones because of the reflowable layout required of PeBL books (i.e., which responds dynamically to the available screen size); however, the design needs to be optimized for smartphones to create a truly usable product on that platform. In general, it is uncommon for users to consume eBook products on smartphones, as the screen is simply too small for normal book pages. This can be an even bigger problem if the chosen PeBL extensions contain interactions and media objects that require a bigger screen.
Because of the reflowable layout of PeBL books, as described above, the book content will adapt to the available screen size. This makes it less important to target your design to a particular brand or size of tablet. In general PeBL is more sensitive to the choice of eReader than the choice of hardware.
If you are planning to use your PeBL books on desktop computers as a default or alternative to tablet consumption, then you will need software that reads EPUB 3 on them. This is often provided as a plug-in to a desktop browser (made by the eReader vendor), but may be a standalone piece of desktop software. A list of desktop eReaders is also available in the eReader compatibility chart.
Note: The ADL reference implementation of PeBL currently runs only on Apple iPads, but there are plans to create Android and desktop browser versions.