title: What do the arrows in the navigator pane on Xcode indicate?
body: <p>In earlier versions of Xcode the source control tool would indicate that you have modified a file by showing a bold 'M' to the right of the file name.</p>
  
  <p>In Xcode 9 I noticed that some of my files now show either an upward or upward facing arrow. What do they indicate?</p>