0ad/binaries/data/mods/public/shaders/glsl/sky.xml

<?xml version="1.0" encoding="utf-8"?>
<program type="glsl">

    <vertex file="glsl/sky.vs">
        <stream name="pos"/>
        <attrib name="a_vertex" semantics="gl_Vertex"/>
    </vertex>

    <fragment file="glsl/sky.fs"/>

</program>