What is this called in the GUI Framework Tag Form toolbox? (see picture)
<p>I would like to know what the section highlighted in red is called in the c# form box:
<a href="https://i.stack.imgur.com/8XsVD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8XsVD.png" alt="enter image description here"></a></p>

<p>Thanks in advance for your help!</p>