XF Files are standard .mid files, but it includes Lyric and TABS.
When you play an XF file, you will see the Lyric and TABS in the screen on your Keyboard.
It's almost like Karaoke files, but with TABS.
The Lyric and TABS will follow the music.
It therefore replaces the paper version of the song, as you can follow it on the screen of your keyboard.
Very handy I think :-)
It's relativ easy to change an .kar file "Karaoke files" to an XF files, but if you only got the plain .mid file it take some time to change it for XF file.
Thats way I would like to share my XF file with others XF files in return :-)
/JAKIV