They are called type suffixes.
Integer type suffixes are: U, L, UL, LU, u, l, ul, lu, Ul, uL, Lu, lU
where U/u = unsigned and L/l = long. Lowercase l is not recommended
unless you want to obfuscate your source code.
Real type suffixes are: F, D, M, f, d, m where F/f = float, D/d =
double. M/m = Decimal