title: Identify invalid characters in text based cell
body: <p>I recently inherited a VBA macro that needs to have validation logic added to it.  I need to be able to determine if any characters in a text based cell are non ASCII characters (i.e. have a binary value > 0x7F).  The cells may contain some carriage control values (particularly linefeeds) that need to be retained (so the CLEAN function does not work for this validation).  I have tried the IsText function, but found that it will interpret UTF-8 character sequences as valid text (which I don't want).</p>
  
  <p>I don't need to actually manipulate the string, I just want to display an error to the user that runs the macro to tell him that there are invalid (non-ASCII) characters in a specific cell.</p>