What exactly is made constant with this type definition?

Question

C++ / C#

What exactly is made constant in such a const std::vector<float>&vector entry, a reference or the vector itself?

Answer 1

Constant vector. You can only call constant methods, you cannot reassign or somehow change them.
But where can there be any misunderstanding here? In C++, you can never change what references refer to. const/not const can only be what it refers to.
Edit: I originally incorrectly called it a constant reference here, but for good reason, it's called a constant reference.