From Wiki Knowledge Base | Teltonika GPS
Numerical value describes start offset and is an optional field.
Numerical value of 20 means that blackbox data is requested starting from 20th latest event.
When # is omitted the latest events are packed to single SMS.
Xn – timestamp in HEX.
Yn – HEX value of event ID.
Zn – HEX value of custom data field (optional).