RT_CFG_Add_Marker: Add a marker at the current location
RT_CFG_Test: 159, 16 (0x9F1020 + unit ID) (0x7D0)
Byte 0: Start / end marker flag
Bytes 1..7: Unused
Start / end marker flag:
128 = Start marker
129 = End marker
On receipt of this message, the unit will add a marker at the current location, only if the start / end marker flag contains one of the valid values.
Note: It is expected that normally this message will be sent to the unit whilst the unit is stationary at the required marker position. The marker heading will be set perpendicular to the last vehicle heading immediately prior to halt.