As mentioned before, when an event arrives, the correlator assigns a timestamp to the event. The timestamp indicates the time that the event arrived at the correlator. If you coassign an event to a variable, the correlator sets the timestamp of the event to the current time in the context in which the coassignment occurs.

The correlator uses clock ticks to specify the value of each timestamp. The correlator generates a clock tick every tenth of a second. The value of an event's timestamp is the value of the last clock tick before the event arrived.

When you start the correlator, you can specify the --frequency hz option if you want the correlator to generate clock ticks at an interval other than every tenth of a second. Instead, the correlator generates clock ticks at a frequency of hz per second. Be aware that there is no value in increasing hz above the rate at which your operating system can generate its own clock ticks internally. On UNIX and some Windows machines, this is 100 Hz and on other Windows machines it is 64 Hz.

When you start the correlator, you can specify the -Xclock option to disable the correlator's internal clock and replace it with externally generated time events. See Externally generating events that keep time (&TIME events).