It is an API, it could have used in any way until it was not prohibited on the documentation.

I don't know of any non base-10 floating point literal. Do you?

Yes, they are even in C++ standard now. http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0245r1.html

Woa! OK, I stand corrected! OK, let me fix that. Thanks for bugging and educating me!