Among the many features often noted on Kindle book sales pages is the “X-Ray function.” Besides sounding like it’s out of a superhero comic book, the option for adding this feature is never offered when writers upload their book at KindleDP, leaving many of them to wonder what it is. Readers looking at a book’s landing page on Amazon.com often have the same reaction.

The X-Ray function allow readers of an ebook to access reference material that KindleDP uploaded to the ereader or app on which you to read the ebook. For example, you might be able to touch a word and access its dictionary definition, return to the first occurrence of a character in a novel, look at location descriptions, or peruse background material about the book. The reference material doesn’t require the user to go to the Internet, which KindleDP views as a distraction to the reader.

Unfortunately, authors can decide what reference materials KindleDP loads and makes accessible via the X-Ray function.

Authors can add metadata, however, that the X-Ray function can detect. This involves installing programs or apps, such as Windows GUI and MobiPerl, though utilizing such tools requires a bit of knowledge about coding.

In any case, authors still can mimic this function, however, by adding links within the text. The links might be to photos, illustrations or descriptions that appear at the back of the ebook. In nonfiction books, such metadata can prove invaluable to readers.