Added a couple notes in the docs:

1) Note about needing GNU Readline or equivalent for tab-completion to work
2) Note about behavior occurring when and empty line is entered is different from parent cmd module

2 files changed, 19 insertions, 2 deletions

diff --git a/docs/index.rst b/docs/index.rst
index ca5e8870..eba90e0b 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -30,6 +30,13 @@ The basic use of ``cmd2`` is identical to that of cmd_.
      app = App()
      app.cmdloop()
 
+.. note::
+
+   The tab-completion capability provided by cmd_ relies on underlying capability provided by GNU readline or an
+   equivalent library.  Linux distros will almost always come with the required library installed.
+   For Mac OS X, we recommend installing the `gnureadline <https://pypi.python.org/pypi/gnureadline>`_ Python module.
+   For Windows, we recommend installing the `pyreadline <https://pypi.python.org/pypi/pyreadline>`_ Python module.
+
 Resources
 ---------
 
diff --git a/docs/overview.rst b/docs/overview.rst
index cb0c80eb..52f46fef 100644
--- a/docs/overview.rst
+++ b/docs/overview.rst
@@ -4,7 +4,7 @@ Overview
 ========
 
 ``cmd2`` is an extension of cmd_, the Python Standard Library's module for
-creating simple interactive command-line applications.  
+creating simple interactive command-line applications.
 
 ``cmd2`` can be used as a drop-in replacement for cmd_.  Simply importing ``cmd2``
 in place of cmd_ will add many features to an application without any further
@@ -14,4 +14,14 @@ Understanding the use of cmd_ is the first step in learning the use of ``cmd2``.
 Once you have read the cmd_ docs, return here to learn the ways that ``cmd2``
 differs from cmd_.
 
-.. _cmd: http://docs.python.org/library/cmd.html
\ No newline at end of file
+.. note::
+
+   ``cmd2`` is not quite a drop-in replacement for cmd_.
+   The `cmd.emptyline() function <https://docs.python.org/3/library/cmd.html#cmd.Cmd.emptyline>`_ is called
+   when an empty line is entered in response to the prompt. By default, in cmd_ if this method is not overridden, it
+   repeats and executes the last nonempty command entered.  However, no end user we have encountered views this as
+   expected or desirable default behavior.  Thus, the default behvior in ``cmd2`` is to simply go to the next line
+   and issue the prompt again.  At this time, cmd2 completely ignores empty lines and the base class cmd.emptyline()
+   method never gets called and thus the emptyline() behavior cannot be overriden.
+
+.. _cmd: http://docs.python.org/library/cmd.html