when is a free function considered the class's interface?

[akrzemi1]

It is not clear how MrDocs determines whether a free function is just a free function or part of some class's interface.

For instance, it decided to blend
https://github.com/cppalliance/capy/blob/develop/include/boost/capy/buffers/make_buffer.hpp
with
https://github.com/cppalliance/capy/blob/develop/include/boost/capy/buffers.hpp

Although decision of the library has likely been to separate the mechanisms of creating the class from the class definition.

The users should probably have some control over this with special annotations.