re class="example">
<img src="img/figure-rendering-tcu.svg" width="480">
<figcaption>An illustration of output from ① no-tcu-support UA, ② conforming UA, ③ reference file</figcaption>
</figure>

<p>The above example uses Ahem; some tests can be written using Ahem. However, many features of <code>text-combine-upright</code> cannot be tested with only a black square glyph. Also the spec requires UAs with OpenType support to use OpenType features on rendering particular properties; to test this, the font