===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/ssh-keygen.1,v
retrieving revision 1.155
retrieving revision 1.156
diff -u -r1.155 -r1.156
--- src/usr.bin/ssh/ssh-keygen.1	2019/01/22 11:40:42	1.155
+++ src/usr.bin/ssh/ssh-keygen.1	2019/01/23 04:51:02	1.156
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: ssh-keygen.1,v 1.155 2019/01/22 11:40:42 djm Exp $
+.\"	$OpenBSD: ssh-keygen.1,v 1.156 2019/01/23 04:51:02 djm Exp $
 .\"
 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -35,7 +35,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: January 22 2019 $
+.Dd $Mdocdate: January 23 2019 $
 .Dt SSH-KEYGEN 1
 .Os
 .Sh NAME
@@ -640,6 +640,12 @@
 .It Fl z Ar serial_number
 Specifies a serial number to be embedded in the certificate to distinguish
 this certificate from others from the same CA.
+If the
+.Ar serial_number
+is prefixed with a
+.Sq +
+character, then the serial number will be incremented for each certificate
+signed on a single command-line.
 The default serial number is zero.
 .Pp
 When generating a KRL, the