Each surface has its own Surface Settings it uses to display the surface in a drawing. This allows the surface to look the same in any drawing you include it in.
TPC also allows you to specify Surface Settings that are unique to a drawing. In this way you can display exactly the information you want for the surface in a drawing without compromising the surface in the other drawings it is included in. You might want to show slope shading in a drawing you submit to the planning board but not in the site plans for each lot. Unique Surface Settings allow you to do just that.
TPC makes a copy of the current Surface Settings and stores them inside the drawing for that surface to use. Any changes you make to the Surface Settings will now be made to this unique copy.
From now on, when you edit Surface Settings for this surface in this drawing, you will be editing the unique Surface Settings you created. TPC keeps track of which settings are unique for you automatically.
You can look at the top of the Surface Settings to see if the settings you are entering are uniuque. If they are, TPC will display Surface Settings Unique to _______ and list the drawing name. This is your indication that these settings are unique.
To remove the unique settings and revert back to the surface's default settings, turn Off the Unique Settings toggle in the Advanced tab.
Unique settings are also removed when you untag a surface in the Surfaces Manager dialog. If a surface is not included in a drawing, the drawing can't store it's unique settings and so it discards them.