title: What does [indeterminate] property exactly do in Angular Material components?
body: <p>I have used ssome of the <a href="https://material.angular.io/components/checkbox/examples" rel="nofollow noreferrer">Angular Material</a> components and there is a property called <code>[indeterminate]</code> that I have serached on the web, but there is not a good explanations what exactly it does. So, could you tell me what it does in the following example?</p>
  <pre><code>&lt;section class=&quot;example-section&quot;&gt;
    &lt;mat-checkbox class=&quot;example-margin&quot;&gt;Check me!&lt;/mat-checkbox&gt;
    &lt;mat-checkbox class=&quot;example-margin&quot; [disabled]=&quot;true&quot;&gt;Disabled&lt;/mat-checkbox&gt;
  &lt;/section&gt;
  
  &lt;section class=&quot;example-section&quot;&gt;
    &lt;span class=&quot;example-list-section&quot;&gt;
      &lt;mat-checkbox class=&quot;example-margin&quot;
                    [checked]=&quot;allComplete&quot;
                    [indeterminate]=&quot;someComplete()&quot;
                    (change)=&quot;setAll($event.checked)&quot;&gt;
        {{task.name}}
      &lt;/mat-checkbox&gt;
    &lt;/span&gt;
    &lt;span class=&quot;example-list-section&quot;&gt;
      &lt;ul&gt;
        &lt;li *ngFor=&quot;let subtask of task.subtasks&quot;&gt;
          &lt;mat-checkbox [(ngModel)]=&quot;subtask.completed&quot;
                        [color]=&quot;subtask.color&quot;
                        (ngModelChange)=&quot;updateAllComplete()&quot;&gt;
            {{subtask.name}}
          &lt;/mat-checkbox&gt;
        &lt;/li&gt;
      &lt;/ul&gt;
    &lt;/span&gt;
  &lt;/section&gt;
  </code></pre>