C# Language Specification

Base types

For purposes of member lookup, a type T is considered to have the following base types:

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  If T is object, then T has no base type.
  
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  If T is an enum-type, the base types of T are the class types System.Enum, System.ValueType, and object.
  
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  If T is a struct-type, the base types of T are the class types System.ValueType and object.
  
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  If T is a class-type, the base types of T are the base classes of T, including the class type object.
  
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  If T is an interface-type, the base types of T are the base interfaces of T and the class type object.
  
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  If T is an array-type, the base types of T are the class types System.Array and object.
  
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  If T is a delegate-type, the base types of T are the class types System.Delegate and object.
  

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