No - the "variables" don't "belong" in the header file.

What you need to ensure is, again:

Symbols may be declared many times;

Symbols must be defined exactly once.

One way to do this ("Erik's way") is to put everything in the header, with a conditional-compilation flag to determine whether declarations or definitions are produced;

Another way ("my way") is to have only declarations in headers, and only definitions in .c files.