bug 954: Changing the simulation time resolution does not work well with attributes

doc/tutorial/source/conceptual-overview.rst

@@ -313,7 +313,7 @@ section, so go ahead and expand that documentation node.  Now, expand the
 ``Debugging`` book and then select the ``Logging`` page.
 
 You should now be looking at the Doxygen documentation for the Logging module.
-In the list of ``#define`` s at the top of the page you will see the entry
+In the list of ``#define``'s at the top of the page you will see the entry
 for ``NS_LOG_COMPONENT_DEFINE``.  Before jumping in, it would probably be 
 good to look for the "Detailed Description" of the logging module to get a 
 feel for the overall operation.  You can either scroll down or select the
@@ -340,6 +340,20 @@ Just as in any C++ program, you need to define a main function that will be
 the first function run.  There is nothing at all special here.  Your 
 |ns3| script is just a C++ program.
 
+The next line sets the time resolution to one nanosecond, which happens
+to be the default value:
+
+::
+
+    Time::SetResolution (Time::NS);
+
+You can change the resolution exactly once (which must be before
+``Simulator::Run ()`` is called, below).  The mechanism enabling this
+flexibility is somewhat memory hungry, so once the resolution has been
+set explicitly we release the memory, preventing further updates.  (If
+you don't set the resolution explicitly, it will default to one nanosecond,
+and the memory will be released when the simulation starts.)
+
 The next two lines of the script are used to enable two logging components that
 are built into the Echo Client and Echo Server applications: