From 06b9a6fd8f04d2c1f68897729a3631d2ff5df84d Mon Sep 17 00:00:00 2001
From: Richard Murray <murray@cds.caltech.edu>
Date: Thu, 4 Jan 2018 22:04:42 -0800
Subject: [PATCH] DOC: update timebase documentation

---
 doc/conventions.rst | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/doc/conventions.rst b/doc/conventions.rst
index 9c3b46ce5..78269c5ea 100644
--- a/doc/conventions.rst
+++ b/doc/conventions.rst
@@ -81,8 +81,9 @@ By default, all systems are considered to be continuous time systems.  A
 discrete time system is created by specifying the 'time base' dt.  The time
 base argument can be given when a system is constructed:
 
-* dt = None: continuous time
-* dt = number: discrete time system with sampling period 'dt'
+* dt = None: no timebase specified
+* dt = 0: continuous time system
+* dt > 0: discrete time system with sampling period 'dt'
 * dt = True: discrete time with unspecified sampling period
 
 Only the :class:`StateSpace` and :class:`TransferFunction` classes allow