You can create your own custom attributes by defining an attribute class, a class that derives directly or indirectly from Attribute, which makes identifying attribute definitions in metadata fast and easy. Suppose you want to tag types with the name of the programmer who wrote the type. You might define a custom Author attribute class:

[System.AttributeUsage(System.AttributeTargets.Class |  
                       System.AttributeTargets.Struct)  
]  
public class Author : System.Attribute  
{  
    private string name;  
    public double version;  
  
    public Author(string name)  
    {  
        this.name = name;  
        version = 1.0;  
    }  
}  

AttributeUsage has a named parameter, AllowMultiple, with which you can make a custom attribute single-use or multiuse. In the following code example, a multiuse attribute is created.

[Author("P. Ackerman", version = 1.1)]  
[Author("R. Koch", version = 1.2)]  
class SampleClass  
{  
    // P. Ackerman's code goes here...  
    // R. Koch's code goes here...  
}