C# Language Specification

Attribute parameter types

The types of positional and named parameters for an attribute class are limited to the attribute parameter types, which are:

• 
  One of the following types: bool, byte, char, double, float, int, long, sbyte, short, string, uint, ulong, ushort.
  
• 
  The type object.
  
• 
  The type System.Type.
  
• 
  An enum type, provided it has public accessibility and the types in which it is nested (if any) also have public accessibility (§17.2).
  
• 
  Single-dimensional arrays of the above types.
  

A constructor argument or public field which does not have one of these types, cannot be used as a positional or named parameter in an attribute specification.

2.