$ZHOROLOG contains the number of seconds that have elapsed since the most recent Caché startup. This is a count, which is independent of clock changes and day boundaries. The value is expressed as a floating point number, indicating seconds and fractions of a second. The number of decimal digits is platform-dependent. $ZHOROLOG truncates trailing zeros in this fractional portion.
This special variable cannot be modified using the SET command. Attempting to do so results in a <SYNTAX> error.
Because of a limitation in the Windows operating system, putting your Windows system into hibernate or standby mode may cause $ZHOROLOG to return unpredictable values. This problem does not affect $HOROLOG or $ZTIMESTAMP values.