getRequires()

    array getRequires(string objectClassName)
This function will return an array of the attributes which the specified objectClass requires based on what you have defined in your slapd.oc.conf file.

Example: 

$ldap = new LDAP();
$oc = "organizationalUnit";
$required = $ldap->getRequires($oc);
echo "ObjectClass '$oc' requires the following attributes:<br>";
for ($ctr = 0; $ctr < count($required); $ctr++)
{
	echo $required[$ctr] . "<br>\n";
}