Can anyone clarify an understanding

Using Arduino Programming Questions
1

I'm happily sending midi from a device to a PC via USB, using the midiusb.h library - all working well.
I am using functions like the one below -
I have the right data for v1,v2,v3 but I do not yet understand what the 0x0B, 0xB0 | signifies, & why it is separated from the data sent with the | character.
I think it is some kind of usb data packet, but how do I know what the values should be? - they always seem to be mirrored, ie 0B then B0, or 08 then 80 - why are they mirrored like that?

void ThreeByteMsg(byte v1, byte v2, byte v3) {
midiEventPacket_t event = {0x0B, 0xB0 | v1, v2, v3};
MidiUSB.sendMIDI(event);

I can't find much info on the midiusb library.
Thx.

2

I can't find much info on the midiusb library.

Even if you could, it wouldn't help much. Your question is about a MIDI message. THAT is what you should be googling. How the library manages packaging your data into a MIDI message is less important that understanding what a MIDI message is, and what the contents of the message mean.