Internal implementation package not meant for direct consumption. Please do not reference directly. Provides the fundamental primitives, classes and base classes that define commonly-used value and reference data types, events and event handlers, interfaces, attributes, and exceptions. This packages represents the core package, and provides the minimal set of types required to build a managed application. Commonly Used Types: System.Object System.Exception System.Int16 System.Int32 System.Int64 System.Enum System.String System.Char System.Boolean System.SByte System.Byte System.DateTime System.DateTimeOffset System.Single System.Double System.UInt16 System.UInt32 System.UInt64 System.IDisposable System.Uri When using NuGet 3.x this package requires at least version 3.4.