Comment by zamadatix

Scancode vs character code is what they are describing:

Games SHOULD use scancodes for positional mappings (like WASD) and rely on the system keymap to decide what letter to display them as. There is no "probably" here, the scancode is the scancode and the keymap is the keymap.

Games OFTEN use the character codes directly regardless if it's for a positional mapping or not. This requires explicit support in the game for each possible system keymap, otherwise you end up with nonsense mappings.