PEP 538: clarify sys.stderr error handler isn't changing

The previous wording suggested that all three standard streams
were affected by the proposed change to the default error handler.

Only stdin and stdout are affected - the default error handler for
stderr continues to be "backslashreplace"

pep-0538.txt

@@ -49,9 +49,9 @@ changed such that:
   locale to the first available locale out of ``C.UTF-8``, ``C.utf8``, or
   ``UTF-8``
 * ``Py_Initialize`` will be updated to treat these potential coercion target
-  locales the same way it already treats the ``C`` locale: the default standard
+  locales the same way it already treats the ``C`` locale: the default ``stdin``
-  stream error handler for these locales will become ``surrogateescape`` (this
+  & ``stdout`` error handler for these locales will become ``surrogateescape``
-  default can be overridden through ``PYTHONIOENCODING`` and
+  (this default can be overridden through ``PYTHONIOENCODING`` and
   ``Py_SetStandardStreamEncoding`` as usual)
 * if ``Py_Initialize`` detects that the legacy ``C`` locale remains active
   (e.g. none of ``C.UTF-8``, ``C.utf8`` or ``UTF-8``
@@ -508,9 +508,9 @@ Changes to the default error handling on the standard streams
 -------------------------------------------------------------
 
 Since Python 3.5, CPython has defaulted to using ``surrogateescape`` on the
-standard streams (``sys.stdin``, ``sys.stdout``, ``sys.stderr``) when it
+standard streams (``sys.stdin``, ``sys.stdout``) when it detects that the
-detects that the current locale is ``C`` and no specific error handled has
+current locale is ``C`` and no specific error handled has been set using
-been set using either the ``PYTHONIOENCODING`` environment variable or the
+either the ``PYTHONIOENCODING`` environment variable or the
 ``Py_setStandardStreamEncoding`` API. For other locales, the default error
 handler for the standard streams is ``strict``.
 
@@ -520,6 +520,9 @@ coercion target locales (``C.UTF-8``, ``C.utf8``, and ``UTF-8``) will be added
 to the list of locales that use ``surrogateescape`` as their default error
 handler for the standard streams.
 
+No changes are proposed to the default error handler for ``sys.stderr``: that
+will continue to be ``backslashreplace``.
+
 
 Changes to locale settings on Android
 -------------------------------------
@@ -597,11 +600,12 @@ By coercing the locale away from the legacy C default and its assumption of
 ASCII as the preferred text encoding, this PEP also disables the implicit use
 of the "surrogateescape" error handler on the standard IO streams that was
 introduced in Python 3.5 ([15_]), as well as the automatic use of
-``surrogateescape`` when operating in PEP 540's UTF-8 mode.
+``surrogateescape`` when operating in PEP 540's proposed UTF-8 mode.
 
-Rather than introducing yet another configuration option to address that,
+Rather than introducing yet another configuration option to adjust that
-this PEP proposes to extend the "surrogateescape" default to also apply to
+behaviour, this PEP instead proposes to extend the "surrogateescape" default
-the three potential coercion target locales.
+for ``stdin`` and ``stderr`` error handling to also apply to the three
+potential coercion target locales.
 
 The aim of this behaviour is to attempt to ensure that operating system
 provided text values are typically able to be transparently passed through a