Assembly: System.Web.Mobile (in System.Web.Mobile.dll)
If you want to use validation, this property must contain a value that represents a valid form ID. The property can be set in code or declaratively, as in the example for the ValidationSummary class.
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
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.