urho3d/SourceAssets/Shaders/Shadow.xml

<shaders>
    <shader name="Shadow" type="vs">
        <option name="Mask" define="ALPHAMASK" />
        <variation name="" />
        <variation name="Skinned" define="SKINNED" />
        <variation name="Instanced" define="INSTANCED" />
    </shader>
    <shader name="Shadow" type="ps">
        <option name="Mask" define="ALPHAMASK" />
    </shader>
</shaders>