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Also, the description of the current chapter or spine element that the reader is currently in should either fall back to the TOC description of the user's location, or simply use that location Exclusively since it guarantees a name and not a default "Current Chapter"
SimplyE shows progress like this:
On the left is the view readers have in the chapter showing progress within the chapter, and chapter name. The way this is presented might not make it clear that the progress is only within the chapter rather than the whole book. In this example, the chapters do not have names only numbers so you see a parenthetical (2) which could add to the confusion since it is not clear what the '2' refers to.
After tapping the top or bottom border, the toolbar appears at the top and a progress bar appears at the bottom. Under the progress bar the same chapter progress annotation, so it is not clear whether the progress bar is for the book overall, or for the chapter.
Open questions: See examples of competitors below. All show progress overall, none show progress within a chapter. Is there any value in showing the progress through a chapter? Does this also frustrate reader expectations? Are they expecting the overall progress? Should we replace chapter progress with book progress?
ibooks shows progress like this:
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