-@itemdef{wxHAS_LARGE_FILES, Defined if wxFile supports files more than 4GB in size.}
-@itemdef{wxHAS_LARGE_FFILES, Defined if wxFFile supports files more than 4GB in size.}
+@itemdef{wxHAS_LARGE_FILES, Defined if wxFile supports files more than 4GB in
+ size (notice that you must include @c wx/filefn.h before testing for this
+ symbol).}
+@itemdef{wxHAS_LARGE_FFILES, Defined if wxFFile supports files more than 4GB in
+ size (notice that you must include @c wx/filefn.h before testing for this
+ symbol).}
+@itemdef{wxHAS_LONG_LONG_T_DIFFERENT_FROM_LONG, Defined if compiler supports a
+ 64 bit integer type (available as @c wxLongLong_t) and this type is
+ different from long. Notice that, provided wxUSE_LONGLONG is not turned
+ off, some 64 bit type is always available to wxWidgets programs and this
+ symbol only indicates a presence of such primitive type. It is useful to
+ decide whether some function should be overloaded for both
+ <code>long</code> and <code>long long</code> types.}