README.md in rb-threadframe-0.39 vs README.md in rb-threadframe-0.40

@@ -1,10 +1,13 @@
 # rb-threadframe
 
-rb-threadframe is a set of patches to Ruby 1.9.2 and a C extension
-that gives introspection access for method call frames.
+rb-threadframe is a set of patches to Ruby MRI 1.9.2 and 1.9.3 that
+adds introspection of call frames and adds other run-time support for debuggers and run-time introspection. 
 
+For MRI 1.9.2, there are additional routines are in a C extension. For MRI 1.9.3, everthing is in a patched Ruby. Necessary patches and some simple patch code are found in this repository though. 
+
 ## Requirements
 
-A patched version of YARV Ruby 1.9.2 (and not any other version Ruby) of is needed.
+Source for Ruby MRI version 1.9.2 or 1.9.3 p327. Patches are provided
+for these two versions only.
 
 See the [wiki](http://github.com/rocky/rb-threadframe/wiki) for more information.