<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<path id="thePath" d="M50 150 L 450 150" />
<pattern id="pat" patternUnits="userSpaceOnUse" x="0" y="0" width="400" height="400">
<text>
<textPath xlink:href="#thePath">This text should be ABOVE the other line.</textPath>
<textPath xlink:href="#thePath"><tspan dy="20">This text should be BELOW the other line.</tspan></textPath>
</text>
</pattern>
<rect width="400" height="400" fill="url(#pat)" stroke="black" stroke-width="1"/>
</svg>