The default implementation of the Description property simply returns this value.
This extra property exists so that you can derive from DescriptionAttribute and provide a localized version. The derived localizable DescriptionAttribute will maintain a private Boolean field to indicate if it has been localized. On the first access to the Description property, it will look up the localized string and store it back in the DescriptionValue property.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2