indicates which symbol on the key will be used, in a vertical direction.
So on a standard US keyboard, the key with the number “1” on it also has the
exclamation point ("!") character on it. The level indicates whether to use
the “1” or the “!” symbol. The letter keys are considered to have a lowercase
letter at level 0, and an uppercase letter at level 1, though only the
uppercase letter is printed.
indicates which symbol on the key will be used, in a vertical direction. So on a standard US keyboard, the key with the number “1” on it also has the exclamation point ("!") character on it. The level indicates whether to use the “1” or the “!” symbol. The letter keys are considered to have a lowercase letter at level 0, and an uppercase letter at level 1, though only the uppercase letter is printed.