Security transparency in CLR 2.0 (.NET 2.0, .NET3.0, .NET 3.5) and in CLR 4.0 (.NET 4.0)

David DeWinter has an excellent series of post on different topics security in both CLR 2.0 and CLR 4.0

Transparency Can Reduce Your Security Footprint – #1
Using Transparency in CLR 2.0 – #2
Transparent Code Behavior in CLR 2.0 – #3
What’s New With Security in .NET 4? – #4
Opting Out of Security Changes in .NET 4 – #5
The AllowPartiallyTrustedCallersAttribute (APTCA) – #6

How to Host a Partial Trust Sandbox – #7
Conditional APTCA in .NET 4 – #8
Hosting Conditional APTCA Assemblies – #9
An Introduction to Security Transparency in .NET 4 – #10
Type Transparency in .NET 4 – #11
Partial Trust, APTCA, and Security Transparency – #12
Transparency and Implicit Static Constructors – #13
Determining the Security Rules for Your Assemblies – #14
The SecurityRulesAttribute – #15
Mixing Level 1 and Level 2 Transparency Rules – #16
How to Build APIs with Transparency in Mind – #17
Asserting for Permissions in .NET 4 – #18