diff -r fb4801478d5d -r a93b74f745a6 hgext3rd/topic/__init__.py
--- a/hgext3rd/topic/__init__.py	Mon Sep 03 17:07:36 2018 +0200
+++ b/hgext3rd/topic/__init__.py	Mon Sep 03 20:53:12 2018 +0200
@@ -29,7 +29,7 @@
 your current topic.
 
 Topic is offering you aliases reference to changeset in your current topic
-stack as 't#'. For example, 's1' refers to the root of your stack, 's2' to the
+stack as 's#'. For example, 's1' refers to the root of your stack, 's2' to the
 second commits, etc. The 'hg stack' command show these number. 's0' can be used
 to refer to the parent of the topic root. Updating using `hg up s0` will keep
 the topic active.
@@ -238,8 +238,8 @@
 def _contexttopicidx(self):
     topic = self.topic()
     if not topic:
-        # XXX we might want to include t0 here,
-        # however t0 is related to  'currenttopic' which has no place here.
+        # XXX we might want to include s0 here,
+        # however s0 is related to  'currenttopic' which has no place here.
         return None
     revlist = stack.stack(self._repo, topic=topic)
     try:
@@ -293,7 +293,7 @@
             elif ttype == 'branch':
                 msg = _('cannot resolve "%s": %s "%s" has only %d non-public changesets')
             raise error.Abort(msg % (name, ttype, tname, len(revs) - 1))
-        # b0 or t0 can be None
+        # b0 or t0 or s0 can be None
         if r == -1 and idx == 0:
             msg = _('the %s "%s" has no %s')
             raise error.Abort(msg % (ttype, tname, name))
@@ -335,7 +335,7 @@
 
     extensions.wrapfunction(cmdutil, 'buildcommittext', committextwrap)
     extensions.wrapfunction(merge, 'update', mergeupdatewrap)
-    # We need to check whether t0 or b0 is passed to override the default update
+    # We need to check whether t0 or b0 or s0 is passed to override the default update
     # behaviour of changing topic and I can't find a better way
     # to do that as scmutil.revsingle returns the rev number and hence we can't
     # plug into logic for this into mergemod.update().