#8213: document behavior of -u on py3k better.

Doc/using/cmdline.rst

@@ -232,8 +232,9 @@ Miscellaneous options
 
 .. cmdoption:: -u
 
-   Force stdin, stdout and stderr to be totally unbuffered.  On systems where it
-   matters, also put stdin, stdout and stderr in binary mode.
+   Force the binary layer of the stdin, stdout and stderr streams (which is
+   available as their ``buffer`` attribute) to be unbuffered.  The text I/O
+   layer will still be line-buffered.
 
    See also :envvar:`PYTHONUNBUFFERED`.
 

Misc/python.man

@@ -165,12 +165,12 @@ and the site-dependent manipulations of
 that it entails.
 .TP
 .B \-u
-Force stdin, stdout and stderr to be totally unbuffered.  On systems
-where it matters, also put stdin, stdout and stderr in binary mode.
-Note that there is internal buffering in readlines() and
-file-object iterators ("for line in sys.stdin") which is not
-influenced by this option.  To work around this, you will want to use
-"sys.stdin.readline()" inside a "while 1:" loop.
+Force the binary I/O layers of stdin, stdout and stderr to be unbuffered.
+The text I/O layer will still be line-buffered.
+.\" Note that there is internal buffering in readlines() and
+.\" file-object iterators ("for line in sys.stdin") which is not
+.\" influenced by this option.  To work around this, you will want to use
+.\" "sys.stdin.readline()" inside a "while 1:" loop.
 .TP
 .B \-v
 Print a message each time a module is initialized, showing the place