Master "Program Change" Up/Down feature

Hi, could you please briefly explain the format of the values that can be entered for program change-up / change-down, and bank change-up / change-down in the webconf and what reasonable or standard values are?
When going through the wiki (where this feature is currently not so well documented) and the forum, I found different notations and I’m not sure what to enter to tie this to an external controller able to send MIDI Control Change and Program Change commands (an akai lpd8).
E.g. I find prefilled (for roland MSB) C#7F / C#00 and B#007F / B#0000, respectively. Does that read 00 = 0, 7F = 127 (in HEX)?
What do B and C stand for? What else can be entered? Why is 2 digit HEX and 4 digit HEX used? Sorry but I’m just getting into this MIDI commands and there is some confusion to it if these are standard midi notations or something specific to zynthian. thanks :slight_smile: