Issue #8840: Make documentation for truncate() clearer
diff --git a/Doc/library/io.rst b/Doc/library/io.rst
index 63895bc..c755a2b 100644
--- a/Doc/library/io.rst
+++ b/Doc/library/io.rst
@@ -320,10 +320,12 @@
.. method:: truncate(size=None)
- Truncate the file to at most *size* bytes. *size* defaults to the current
- file position, as returned by :meth:`tell`. Note that the current file
- position isn't changed; if you want to change it to the new end of
- file, you have to :meth:`seek()` explicitly.
+ Resize the stream to the given *size* in bytes (or the current position
+ if *size* is not specified). The current stream position isn't changed.
+ This resizing can extend or reduce the current file size. In case of
+ extension, the contents of the new file area depend on the platform
+ (on most systems, additional bytes are zero-filled, on Windows they're
+ undetermined). The new file size is returned.
.. method:: writable()