What considerations should be made when replacing $HTTP_* variables with superglobal arrays in PHP scripts to ensure global validity?

When replacing $HTTP_* variables with superglobal arrays in PHP scripts, it is important to consider the compatibility with older code that may still rely on the deprecated variables. To ensure global validity, you should update all references to the deprecated variables with their corresponding superglobal array elements. Additionally, make sure to sanitize and validate user input to prevent security vulnerabilities.

// Replace $HTTP_* variables with superglobal arrays
$var = $_GET['var']; // instead of $HTTP_GET_VARS['var']