A request XML packet changing the recursion type includes the set-recursion operation node:
<packet version="1.4.2.0">
<dns>
<set-recursion>
¡
</set-recursion>
</dns>
</packet>
The set-recursion node is presented by type DNSSetRecursionInputType (dns_input.xsd) and structured as follows:

plesk_dns.xsd). Allowed values: on | off | local | localnets.