Switch between XG - GS - GM

[JAKIV]

Hi
I am a bit confused about using XG GS and GM.
I know that these are different MIDI standards and XG was specially developed by Yamaha.
I have seen the below Sy*** codes in several places on the web, but do not understand the reason for using them.
But is it something you can turn off and on yourself.
If it is, where do you do it on the Keyboard and why would you do it?
System Exclusive message examples:
• GM System On = F0 7E 7F 09 01 F7
• XG System On = F0 43 10 4C 00 00 7E 00 F7
• XG Works On = F0 43 76 1A 10 01 01 01 01 01 01 01 01 F7
• Yamaha = F0 43 73 39 F1 00 46 00 F7
• XG Reset = F0 43 10 4C 00 00 7F 00 F7

/ JAKIV

[pjd]

Way back when, different manufacturers invented their own proprietary sound/effect architectures. General MIDI was defined by an industry-wide committee. XG was defined by Yamaha. GS was defined by Roland.

Each manufacturer defined MIDI messages that were (mostly) specific to their sound architecture. At the time, GM, XG and GS mainly pertained to Standard MIDI Files (SMF), in other words, song files.

So, someone might have an XG song created for Yamaha keyboards. Or maybe a GS song created for Roland.

The MIDI System Exclusive messages in your post usually appear at the beginning of a MIDI song file (SMF). They tell the keyboard what standard to use during playback (GM, XG or GS).

Enough info? It's easy to get too technical with this subject. 

Best -- pj

[JAKIV]

Thank you. 
So it is in no way something you manually turn on and off unless MIDI files are being played.  And here it typically happens completely by itself if it is embedded in the start of the MIDI file itself.  Then I understand.  Thanks for the help.
/ JAKIV