an></code><span class="classifier"><code class="docutils literal notranslate"><span class="pre">&lt;class</span> <span class="pre">'float'&gt;</span></code>   <em>&lt;optional&gt;</em></span></dt><dd><p>Description: Only allow particles to be below this vertical position</p>
<ul class="simple">
<li><p>default: <code class="docutils literal notranslate"><span class="pre">None</span></code></p></li>
<li><p>data_type: <code class="docutils literal notranslate"><span class="pre">&lt;class</span> <span class="pr