As Geoff has said, the XF specification is a Yamaha extension to General MIDI.
The SysEx messages are used to create styles for modern Yamaha keyboards.
The various elements of meta data are built into various, old sequencing programs from Yamaha such as XGworks and SOL2.
These date from the lateish nineties to early 2000's.
An extremely fine gentleman by the name of Jørgen Sørensen has a web site with a lot of resources on it.
Amongst them are the XG and XF specifications which can be found here:
JoSoSoft Web Site specs
You'll find the data you need starting on page 19 of the XF spec.