| TSSS | Timestamp Sub-seconds The value in this field has the sub-second representation of time, with an accuracy of 0.46 ns. When the TSCTRLSSR bit is set in the , each bit represents 1 ns and the programmed value should not exceed 0x3B9A_C9FF. |
| ADDSUB | Add or Subtract Time When this bit is set, the time value is subtracted with the contents of the update register. When this bit is reset, the time value is added with the contents of the update register. |