Customers may require the format of UBX messages for a specific data topic, such as pp/ubx/0236/ip (Key Delivery). U-Blox provides the format of UBX messages in our publicly available F9 documentation. The location of the format for UBX messages is listed on page 193 under 'UBX-RXM-SPARTNKEY (0x02 0x36)'. Our F9 documentation can be found here.