When it is necessary to specify time intervals to Heartbeat, times can be specified as a floating point number followed by an optional units-specifier. The units specifiers allowed are:
ms - milliseconds
us - microseconds
usec - microseconds
If a units specifier is omitted, seconds are assumed. The following are examples of legal Heartbeat time interval specifications:
1 100ms 100000us .001 1500.1ms
In spite of the apparent precision inherent in the format described above, in the end, the time given is converted into an integer number of milliseconds.