Dear Sir/Madam, *Bug: *In section 2.2.2. on page http://docs.python.org/py3k/tutorial/interpreter.html you mention "On Windows systems, there is no notion of an “executable mode” ".** This is wrong. Since Windows NT4 and onwards, there is a notion of a "path extension", which is similar to the Unix executable mode, but invoked differently. *Solution:* 1. Using the GUI: a. Right-click on "My computer" b. go to "properties" c. go to "environment variables" (dependent on the OS: NT 4.0, W2K, XP, Vista, W7) d. add the string ";PY" to the end of the existing string OR 2. Using the Command line (temporary for that command interpreter only until it is exited) At the CLI (cmd.exe; commnd.com) ">" type: SET PATHEXT=%PATHEXT%;.PY Python executables can now be executed on a command line without specifically invoking the Python interpreter as the Python installer automatically associates .py files with python.exe. (Which is a prerequisite) *Example:* C:\Program Files\Python\Tools\Scripts>SET PATHEXT=%PATHEXT%;.PY C:\Program Files\Python\Tools\Scripts>2to3.py At least one file or directory argument required. Use --help to show usage. HTH, Fabrizio Marana