Under MS, Nullable<> is declared as: "Nullable<T> where T: struct, new()".

This construct is not allowed for regular C# code, but it happens to work for Nullable.

This property might be verified by running the following program under MS and mono:

using System;
class Driver
{
	public static void Main ()
	{
		Console.WriteLine (typeof (Nullable<>).GetGenericArguments()[0].GenericParameterAttributes);
	}
}


MS reports: 
NotNullableValueTypeConstraint, DefaultConstructorConstraint

Mono reports:
NotNullableValueTypeConstraint


This is not a SRE issue as the API allows for such constraints to be defined.