🚀 go-pugleaf

The 0.9 documentation release of the NeXT systems contained a section on
objective-C language specification as released by Stepstone 1988. This section
appeared in the Documentation appendices volume. Page 4-18 of such section
constains an example of an interface file which " contain type information and
function declaration [..] to more reliably and efficiently access the class". 
Such interface contains declarations of 3 C-functions tagged with EXPORT,
instead of "+" or "-". Thus they must not be methods. What are they? Are they
C-functions accessible to a consumer of the class?.
 In the implementation of
that interface (on page 4-19) the following comment is found at the end of
it : //Definition of Private Methods and Functions. 
I can infer that a private function refers to a C-function defined and implemen-
ted in the implementation file; but, What is a private method? how to define
it? Can we extend the set of methods in the implementation?

Thanks
J. Nino