relativeMachineMicros(): Decimal;
The relativeMachineMicros method of the Application class returns a high-accuracy machine-relative time in microseconds (that is, millionths of a second). This method is based on a hardware timer. (Internal ticks per second can vary, depending on hardware.)
The time is relative to the machine that is executing the method, which is the application server host when the application is run in JADE thin client mode. This relative time value may wrap around after a period of machine up-time. The period of up-time is hardware-dependent.
As the maximum precision of the timer is 19 digits, you should use a Decimal[19] (or higher) precision decimal for storage and computation.