[CheckId] CA2131 [Warning] CA2131: Security critical types may not participate in type equivalence [Description] 
A type participates in type equivalence and either the type itself, or a member or field of the type, is marked by using the SecurityCriticalAttribute attribute. This rule occurs on any critical types or types that contain critical methods or fields that are participating in type equivalence. When the CLR detects such a type, it does not load it with a TypeLoadException at run time. Typically, this rule is raised only when users implement type equivalence manually instead of in by relying on tlbimp and the compilers to do the type equivalence.