.NET type with a "2" suffix?

I vaguely remember there is a .NET type name with the suffix "2". I can't remember exactly which one it is though. Can anyone point it out to me? Thanks

From stackoverflow

• There are a couple: ITypeLib2, ITypeInfo2, RC2, IDesignerLoaderHost2, and X509Certificate2.

  Happy reading :-D

  sixlettervariables : Snarky additions: `Int32`, `UInt32`, `HMACSHA512`, `SHA512`, `BitVector32`, `SqlInt32`...

• There are a lot of them...For example some of the code extensibility uses this.

  We're going to need some more information for the specific type you want because there are far more than one of these types of objects.

  CodeModel to CodeModel2

• At one time there was a plan to add DateTime2, but it was later renamed DateTimeOffset. See BCL blog for details.