bpo-38388: Document pickle protocol version 5 (GH-16639)
diff --git a/Doc/library/pickle.rst b/Doc/library/pickle.rst
index eb58178..779b60e 100644
--- a/Doc/library/pickle.rst
+++ b/Doc/library/pickle.rst
@@ -136,7 +136,7 @@
generated by :mod:`pickle`. :mod:`pickletools` source code has extensive
comments about opcodes used by pickle protocols.
-There are currently 5 different protocols which can be used for pickling.
+There are currently 6 different protocols which can be used for pickling.
The higher the protocol used, the more recent the version of Python needed
to read the pickle produced.
@@ -160,6 +160,10 @@
Refer to :pep:`3154` for information about improvements brought by
protocol 4.
+* Protocol version 5 was added in Python 3.8. It adds support for out-of-band
+ data and speedup for in-band data. Refer to :pep:`574` for information about
+ improvements brought by protocol 5.
+
.. note::
Serialization is a more primitive notion than persistence; although
:mod:`pickle` reads and writes file objects, it does not handle the issue of