IdnMapping.AllowUnassigned Property


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Gets or sets a value that indicates whether unassigned Unicode code points are used in operations performed by members of the current IdnMapping object.

Namespace:   System.Globalization
Assembly:  mscorlib (in mscorlib.dll)

Public Property AllowUnassigned As Boolean

Property Value

Type: System.Boolean

true if unassigned code points are used in operations; otherwise, false.

A registered domain name cannot contain unassigned code points. Consequently, the default value of the AllowUnassigned property is false. The IDNA specification permits unassigned code points only in queries for matching strings (that is, in domain name lookup). For more information about the use of unassigned code points in domain names, see RFC 3454, "Preparation of Internationalized Strings (stringprep)" and RFC 5891, "Internationalized Domain Names in Applications (IDNA): Protocol".


If theAllowUnassigned property is false, the behavior associated with the property depends on the underlying operating system. On Windows 8, the IdnMapping class conforms to IDNA 2008, which is based on the Unicode 6.0 standard. On previous versions of Windows, the IdnMapping class is based on IDNA 2003, which is based on Unicode 3.x. Some code points that were unassigned in IDNA 2003 have been assigned characters and are supported in IDNA 2008. For example, U+0221 was introduced in Unicode 4.0. On Windows 8, it is encoded as "xn—6la". On previous versions of Windows, it throws an ArgumentException exception.

Universal Windows Platform
Available since 10
.NET Framework
Available since 2.0
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