The program for determining the minimum working version of Net. Framework (C#)?

Question

.NET

Good afternoon.
Once upon a time I heard about a special program that determines the minimum possible version of Net from the source code. Framework when compiling while keeping the code working. I can't find this program.
Please tell me the tools for automatic targeting of the minimum version of Net. framework for the project.

Answer 1

It seems that there is such a thing in " .Net Reflector ". He is, however, sometimes buggy. But, in general, the rules of the program.