title: Differences between OSX's .pkg and .pkg.mpkg installers
body: <p>I'm fighting with OSX's packageMaker as it doesn't allow me to create a '.pkg'. Instead it's forcing me to make a '.pkg.mpkg'.</p>
  
  <p>This seems like a stupid question I should be able to respond with a couple of google searches, but I'm not being able to find much info about this.</p>
  
  <p>Could anyone explain the main differences between them and if you know the restriction for which you have to use one or the other?</p>