What is the prefix for base64

Question

I am making a thing that I do not wish to tell you what it is (yet), and would like to know if there is a prefix to denote base 64 numbers in c similar to hex's 0x(number) and binary's 0b(number).

Does this happen to exist, and, if so, does anyone know what the prefix is?

Answer 1

I'm always forgetting this too and every time I google it, I get this post that no one has ever answered... here:

data:image/png;base64,