Corel switched from straight number to the "X" factor with version X3, which followed v. 12, possibly for the same reason there aren't many 13th floors in buildings. Version X5 not only moves the product forward, it also takes an interesting and welcome step backward, because it comes with a hardcover manual the likes of which we're seeing less and less of these days as companies offer either online or PDF manuals.
Both manual types have their advantages. Online and Acrobat files are easier to manage, cheaper to publish (and kill fewer trees, if you're into that kind of thing) and are more easily searchable than a print manual. On the other hand, I like being able to sit the print manual beside me on the desk and look at its hints while my document is open in front of me on the screen.
