What is "merge layer" in Ansoft Designer? 50 point

ansoft designer layout gerbers

Dear Folks,

When I place a coupled stripline circuit component STLCPL2 (I was going through the differential pair example in Designer manual) in Ansoft Designer schematic windows, a dialog popped up asking whether or not to merge layers. Could anyone tell me what does it mean?

I looked through the User guide and online help but found no answer. My only background is under graduate EM/microwave class so I would like the answer to be as detail as possible. Specifically, I want to know

1. What is the purpose of merging layers?
2. In the differential pair example, if I choose merge layer, what is the consequences?
3. What does "flip source before merging" mean?

50 points will be donated for the 1st guy who answered the question satisfiably.
Thanks!

what does it mean to merge layers

I don't use AD so this is not a definitive answer.... but typically with layout editors "merge layers" will combine polygons (on the same or different layers) that are connected or overlapping into a single polygon. This is usually done to clean up extraneous lines before exporting a layout in Gerber format.

Hope that helps!