View a Discussion Thread 
Viewing all comments
 - View a Comment by clicking on the desired subject.
- Add a Comment to the current Discussion Thread by clicking on the
'Add Comment' button. 
Viewing a specific comment
 - Click on the 'Reply' button to reply to the viewed Comment.
NB.  If no 'Discussion Thread' exists for the current document, the
user may click on 'New' to create a discussion or 'Cancel' to to return
to the previous screen.