Apple’s naming convention for its 9.7” tablets has been far less consistent than with its other iOS-powered devices; the iPhone fell into a fairly standard routine when the second-generation iPhone 3G was released in 2008, and the iPad mini has been even more consistent, simply numbering its four models one after the other. On the other hand, following the 2011 debut of the “iPad 2” — a model that remained on sale for longer…