New environment variable PYTHONIOENCODING.
diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index a6ab7ad..7d9ecad 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -481,6 +481,13 @@
 
    .. versionadded:: 2.6
 
+.. envvar:: PYTHONIOENCODING
+
+   Overrides the encoding used for stdin/stdout/stderr, in the syntax
+   encodingname:errorhandler, with the :errors part being optional.
+
+   .. versionadded:: 2.6
+
 
 .. envvar:: PYTHONNOUSERSITE