4fd402ae__Controls_in_Practice___Page_5__Description
[Attribute] DefaultValue [Operates On] Property [Description] 
The .NET framework distinguishes between an initial value of a property and a default value; this attribute does not assign an initial value; it determines only whether the property is serialized in the list of property assignments in your winformapp.Designer.cs file. See MSDN for more details.
.NET Building Blocks: Custom User Controls in Practice : Page 5