diff -r be3b41703822 Doc/library/linecache.rst
--- a/Doc/library/linecache.rst	Tue Mar 10 16:32:50 2015 +0100
+++ b/Doc/library/linecache.rst	Tue Mar 10 10:44:11 2015 -0700
@@ -9,7 +9,8 @@
 
 --------------
 
-The :mod:`linecache` module allows one to get any line from any file, while
+The :mod:`linecache` module allows one to get a line from a Python source file,
+or another UTF-8 text file, while
 attempting to optimize internally, using a cache, the common case where many
 lines are read from a single file.  This is used by the :mod:`traceback` module
 to retrieve source lines for inclusion in  the formatted traceback.
@@ -58,3 +59,8 @@
    >>> linecache.getline('/etc/passwd', 4)
    'sys:x:3:3:sys:/dev:/bin/sh\n'
 
+.. note::
+
+   This module looks for an :ref:`encoding comment <tut-source-encoding>` in
+   the first two lines of the file to determine what text encoding to use.
+   If this isn't present, the file must be readable as UTF-8.