Also as a note, "3.0" is a very specific version of Rockbox. All later versions are not "Rockbox 3" they're just later builds of Rockbox with their own SVN versions.
All previous versions were not "Rockbox 2", they were just builds of Rockbox with their own SVN versions.
Release numbers are numbers for specific releases, not categories like how "Windows 95" covers that version of windows, and all its later updates. They do not cover later updates with Rockbox.