+.Pp
+Prior to Mac OS X 10.5, only bundles could be unloaded. Starting in Mac OS X 10.5,
+dynamic libraries may also be unloaded. There are a couple of cases in which a
+dynamic library will never be unloaded: 1) the main executable links against it,
+2) An API that does not supoort unloading (e.g. NSAddImage()) was used to load
+it or some other dynnamic library that depends on it, 3) the dynamic library
+is in dyld's shared cache.