It's essentially syntactic sugar enforced by the compiler. By convention, you can refer to an Attribute without the suffix.
http://msdn.microsoft.com/en-us/library/84c42s56(v=vs.110).aspx
By convention, the name of the attribute class ends with the word
Attribute. While not required, this convention is recommended for
readability. When the attribute is applied, the inclusion of the word
Attribute is optional.
