> Usage of lowercase alphabets in hex literals (0xab123cdef as opposed to 0xAB123CDEF): hex_literal_case = Lower

Anytime numbers and letters are mixed, it's more readable if the letters are lowercase. It's easier to read the variable heights - numbers are usually capital letter height, sometimes with descenders - and avoids confusing 0O, I1, even 8B and 5S (think of a degraded printed serial number, poor lighting, etc.). There's only l problem that persists.