 <dd>
  <p>Gain envelope parameters.</p>
  <ul>
  <li><code>A</code>: Attack time.</li>
  <li><code>D</code>: Decay time.</li>
  <li><code>S</code>: Sustain amplitude.</li>
  <li><code>R</code>: Release time after note-off.</li>
  </ul>
  </dd>
  </dl>
  <h3 id="oscillator"><a href="#oscillator" class="header-anchor"
  aria-hidden="true">Oscillator</a></h3>
  <p>UltraSynth has 2 oscillators. The parameters of each oscillator
  matchs to X or Y axis of X-Y pad.</p>
  <dl>
  <dt>Pitch</dt>
  <dd>
  <p>Oscilla