File: Core\CSharp\System\Windows\RoutingStrategy.cs
Project: wpf\src\PresentationCore.csproj (PresentationCore)

using System;
namespace System.Windows
{
    /// <summary>
    ///     Routing Strategy can be either of 
    ///     Tunnel or Bubble
    /// </summary>
    /// <ExternalAPI/>
    public enum RoutingStrategy
    {
        /// <summary>
        ///     Tunnel 
        /// </summary>
        /// <remarks>
        ///     Route the event starting at the root of 
        ///     the visual tree and ending with the source
        /// </remarks>
        Tunnel,
        
        /// <summary>
        ///     Bubble 
        /// </summary>
        /// <remarks>
        ///     Route the event starting at the source 
        ///     and ending with the root of the visual tree
        /// </remarks>
        Bubble,
 
        /// <summary>
        ///     Direct 
        /// </summary>
        /// <remarks>
        ///     Raise the event at the source only.
        /// </remarks>
        Direct
    }
}