Launch Expiry Time
Normal/Absolute Mode
In the normal mode, when the LEOV (Launch Expiry Offset Valid bit of MTL_TBS_CTRL register) is set, the 
Launch Expiry Offset (LEOS field of MTL_TBS_CTRL register) determines the maximum amount of time a 
frame is eligible for launch, starting from the time the frame becomes eligible for launch.
The Launch Expiry Offset is a 24-bit value defined in 256ns units, with a maximum possible value of 
999,999,999 ns (0x3B9AC9FF).
Launch Expiry Time = (Launch Time[39:8] + LEOS[32:8]) * 256ns
The packet with a specific Launch time is considered eligible for transmission when the Launch time is less 
than the System Time and (if LEOV is set) the System Time is less than the Launch Expiry time. 
When the System time is greater than the Launch Expiry time the frame is categorized as expired and is 
dropped from the MTL FIFO.翻译