Current-time operators

Use these operators to specify conditions on the current time.

The current time represents a time point. You can refer to a period in a time scale that contains the current time. The current time refers explicitly or implicitly to the parameter now.

For more information about the current time, see Reasoning over time and events.

Table 1. Current time
Operator	Example	Comments
`now`	now is 1 day 6 hours before the scheduled departure date of 'the flight'
`the current year`	the current year includes the scheduled arrival date of 'the flight'	`the current year` is equivalent to `the calendar year of now`
`the current month`	the current month is the calendar month of the scheduled arrival date of 'the flight'	`the current month` is equivalent to `the calendar month of now`
`the current week`	the current week ends at the scheduled arrival date of 'the flight'	`the current week` is equivalent to `the calendar week of now`
`the current day`	the current day is the calendar day of the scheduled arrival date of 'the flight'	`the current day` is equivalent to `the calendar day of now`
`the current hour`	the current hour starts at the scheduled departure date of 'the flight'	`the current hour` is equivalent to `the hour of now`
`the current minute`	the current minute is the minute of the scheduled arrival date of 'the flight'	`the current minute` is equivalent to `the minute of now`
`the current second`	the current second is the second of the scheduled arrival date of 'the flight'	`the current second` is equivalent to `the second of now`
`today`	the scheduled arrival date of 'the flight' is during today	`today` is equivalent to `the calendar day of now`
`yesterday`	the scheduled departure date of 'the flight' is during yesterday
`tomorrow`	the scheduled arrival date of 'the flight' is during tomorrow
`the last period of <calendar duration>`	the last period of 1 month	This operation is based on the parameter `now`. However the value of `now` is not included in the time period.
`the next period of <calendar duration>`	the next period of 7 days	This operation is based on the parameter `now`. However the value of `now` is not included in the time period.

Example: the current month

The following rule checks for closed airports during this month:

when an airport closed event occurs
if
    the number of airport closed events during the current month is more than 4
then
    print “More than 4 airports have been closed during this month.”;