Can someone please explain sheet layers to me. Here's my situation: I started a drawing and referenced in a base plan. I then mapped over pertinent existing condition info and created a viewport on an existing conditions sheet layer. I moved on to create option 1 for the client and created a viewport on option 1 sheet layer. And finally created an option 3 viewport on option 2 sheet layer. It was my impression the other sheet layers would not be modified and would be the same when I went back to them to easily print what I needed. Instead modifications, not all, are showing up on my 3 different sheet layers. What am I doing wrong? thanks for your help.