Embedding an XDocument within XAML

Question

How can I embed an XDocument within XAML? I've got the following but Visual Studio won't let me put any XML in the XDocument:

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:xlinq="clr-namespace:System.Xml.Linq;assembly=System.Xml.Linq"
    x:Class="SomeApp.SomeWindow">
    <Window.Resources>
        <xlinq:XDocument x:Key="SomeXDocument">
            <!-- How can I put XML here? -->
        </xlinq:XDocument>
    </Window.Resources>
</Window>