Is it possible for a .Net 3.5-based web application to use 2.0-based libraries?
I feel like this is a dumb question and I'm missing something, but I haven't even figured out how to search for this one :(
Can an application written to target the .Net 3.5 Framework utilize libraries that were written in the 2.0 Framework?
Additional information in the answer such as the "why" and/or how this information was found would be helpful!
Yes you can. The underlying runtime hasn't changed, it's still CLR v2.0 and c#3 still compiles to 2.0 MSIL which is executed on the 2.0 CLR. Also ASP.NET is still effectively at version 2.0 because the core underpinnings of that haven't changed (C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll).
.NET 3.5 is an additive framework update, not a replacement. You will still be using v2.0 portions of the BCL and FCL at the same time as using 3.0 and 3.5.
Update: Just in case you're interested, I asked a question a while back about 2.0 code consuming 3.5 assemblies which is the other way round:
Hope that helps Kev