How can the behavior of links within a PHP menu be controlled to open content within the same window instead of a new window?

To control the behavior of links within a PHP menu to open content within the same window instead of a new window, you can use the target attribute within the anchor tag. Set the target attribute to "_self" to open the link in the same window.

<ul>
    <li><a href="page1.php" target="_self">Page 1</a></li>
    <li><a href="page2.php" target="_self">Page 2</a></li>
    <li><a href="page3.php" target="_self">Page 3</a></li>
</ul>