In https://lists.oasis-open.org/archives/docbook-tc/201509/msg00015.html, Norman Walsh, TC Chair, reports: 

Subject: Second review period closed

From: Norman Walsh <ndw@nwalsh.com>
To: docbook-tc@lists.oasis-open.org, docbook-comment@lists.oasis-open.org
Date: Wed, 23 Sep 2015 16:04:23 -0500

Hello world,

The second review period for DocBook Version 5.1 has closed. No
comments were received.

                                        Be seeing you,
                                          norm