If you think about it, an ePub is much like a web site, only designed specifically to be viewed on an electronic device. In fact, if you were to crack open an ePub package you would find that, like a web site, it is comprised of one or more HTML files, with supporting resources and CSS style files. And, ust like a web site, one consideration for its design has to do with the speed in which each page, or HTML file, will load. Nothing will put a reader off more than having to wait more than a few seconds for the book to open.
For this reason you may decide to use InDesign’s book feature for creating any publication that is more than a few pages long. As each document for the book exports as a separate HTML document insuring shorter loading times. Even smaller publications can benefit from using the book format to control page breaks.
When considering the design of an ePub publication there may be any number of reasons why you would want to have control over where page breaks occur. Consider the following:
For this and a number of other reasons you may want to create major sections of the publication as separate files and bring then together as a book prior to exporting to ePub. Using a book format gives you, the designer, the most control over page breaks.
Additionally, InDesign gives you many options for controlling page breaks, whether you use the book format or not.
Of course you use paragraph and character styles exclusively for styling all text within your InDesign ePub publication. But paragraph styles can also be designated to break the pubication into designated book sections. In the Export Tagging section for Paragraph Style Options, checking the Split Document (EPUB only) option sets the style up. But unless Based on Paragraph Style Export is checked in the Advanced page for EPUB Export Options, the document will not be split. With the option checked, the document is split into separate HTML files at each point where the paragraph style is used. In later versions of InDesign, more than one paragraph style can be designated, giving the designer more options than just splitting a document at chapter heads.
At the point of export, the EPub Export Options dialog now gives you even more options for splitting a document. In addition to splitting based on paragraph style export settings, you can designate a paragraph style to use for splitting the document from the drop down in the Advanced panel (Split Document:). Using this option you can choose the specific paragraph style from its drop down. But in this instance, unless you select Based on Paragraph Style Export, only one paragraph style or Do Not Split can be chosen.
With version CC of InDesign, object styles can now play a more predominate role in determining the layout for a publication export. The Export Options section for the Object Style Options dialog allows the designer to determine Custom Layout settings for objects assigned an object style on an individual style basis. With Custom Layout checked, you can set up alignment and spacing as well as determine if a page will break before, after, or before and after the image. This sets the page-break-after and/or page-break-before attributes for the object style CSS selector. This does not cause the document to be split, however; just page breaks within the HTML file display.
At the point of export, you can set an option for inserting a page break, after, before, or after and before images. This setting is global and will apply to all images that have not had this property set otherwise. For instance, an image that is assigned an object style may override this option as will a setting established for individual images in the Object Export Options dialog (accessed from the Object’s Export Options menu).
Another improvement found in InDesign CC has to do with the table of contents. In this version the table of contents option goes under the heading Navigation (in the General section for EPUB Export Options). This option now allows Navigation to be based on a table of contents style or Filename. When TOC Style is chosen you then select the name of the Table of Content style from the adjacent dropdown.
Even when using the book option I prefer using the TOC Style. You can set up a TOC Style to display the publication’s navigation exactly the way you want it. Here paragraph styles for each level you want linked can be assigned as part of the style. And, should you want a physical table of contents to be included in your ePub in addition to the navigational table of content, you can generate the table using this style. If you haven’t used a style to generate a physical table of contents, you may be concerned that page number references show up on the page. Rest assured, the numbers are dropped when the page is exported to ePub. Just make sure to check the option Make text anchor in source paragraph when you create the content for the page.
If exporting a book (.indb file), make sure the table of contents style belongs to the document designated as the Style Source. And, of course, you export to ePub using the book’s contextual menu rather than from InDesign’s File menu.