-methods of that particular class. This method is not inherited, and
-is thus not called as initializer for a subclass that doesn't define
-it itself. Thus, each +initialize method is called exactly once (or
-never if no methods of that particular class is never called).
-Besides this, it is allowed to have several +initialize methods, one
-for each category. The order in which these (multiple methods) are
-called is not well defined. I am not completely certain what the
-semantics of this method is for other implementations, but this is
-how it works for GNU Objective C.
+methods of that particular class. For the GNU runtime, this method is
+not inherited, and is thus not called as initializer for a subclass that
+doesn't define it itself. Thus, each +initialize method is called exactly
+once by the runtime (or never if no methods of that particular class is
+never called). It is wise to guard against multiple invocations anyway
+to remain portable with the NeXT runtime. The runtime invocation of
+this method is thread safe.