Extensions Class
This class contains the LINQ to XML extension methods that enable you to evaluate XPath expressions.
Assembly: System.Xml.Linq (in System.Xml.Linq.dll)
There is some performance penalty for using these methods. Using LINQ to XML queries yields better performance.
Although the ordering of returned collections is not specified in the XML XPath Language 1.0 Recommendation, this extension method returns nodes in document order.
Note that nodes are returned in document order even when you use a reverse axis, such as preceding-sibling or ancestor-or-self.
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.