Clarify backwards compatibility.

pep-3105.txt

@@ -93,9 +93,23 @@ Backwards Compatibility
 =======================
 
 The changes proposed in this PEP will render most of today's ``print``
-statements invalid, only those which incidentally feature parentheses
+statements invalid.  Only those which incidentally feature parentheses
 around all of their arguments will continue to be valid Python syntax
-in version 3.0.
+in version 3.0, and of those, only the ones printing a single
+parenthesized value will continue to do the same thing.  For example,
+in 2.x::
+
+    >>> print ("Hello")
+    Hello
+    >>> print ("Hello", "world")
+    ('Hello', 'world')
+
+whereas in 3.0::
+
+    >>> print ("Hello")
+    Hello
+    >>> print ("Hello", "world")
+    Hello world
 
 Luckily, as it is a statement in Python 2, ``print`` can be detected
 and replaced reliably and non-ambiguously by an automated tool, so