What does the colon mean in struct declarations in C?

Reading the code of TeXmacs, I saw this:

struct texmacs_input_rep : concrete_struct {
...
};

What does that mean?

This syntax is defined in the C standard, p113, but I didn't find the meaning of it, but that's because I don't know how to read grammar rules.

Because concrete_struct is another struct, that contains functions looking like a constructor and a virtual destructor, and because I read elsewhere that classes in C++ are actually struct with public members by default, I guess that this is the way of doing inheritance with struct in C (because it is the C standard...).

Is this correct?