System.Security.Permissions.IsolatedStorageFilePermission.Union C# (CSharp) Method

        public override IPermission Union(IPermission target)
        {
            if (target == null)
            {
                return this.Copy();
            }
            else if (!VerifyType(target))
            {
                throw new 
                    ArgumentException(
                                    String.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("Argument_WrongType"), this.GetType().FullName)
                                     );
            }
            
            IsolatedStorageFilePermission operand = (IsolatedStorageFilePermission)target;
    
            if (this.IsUnrestricted() || operand.IsUnrestricted()) 
            {
                return new IsolatedStorageFilePermission( PermissionState.Unrestricted );
            }
            else
            {
                IsolatedStorageFilePermission union;
                union = new IsolatedStorageFilePermission( PermissionState.None );
                union.m_userQuota = max(m_userQuota,operand.m_userQuota);   
                union.m_machineQuota = max(m_machineQuota,operand.m_machineQuota);  
                union.m_expirationDays = max(m_expirationDays,operand.m_expirationDays);    
                union.m_permanentData = m_permanentData || operand.m_permanentData; 
                union.m_allowed = (IsolatedStorageContainment)max((long)m_allowed,(long)operand.m_allowed); 
                return union;
            }
        }   

		public void Union_DifferentPermissions ()
		{
			IsolatedStorageFilePermission a = new IsolatedStorageFilePermission (PermissionState.None);
			SecurityPermission b = new SecurityPermission (PermissionState.None);
			a.Union (b);
		}