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Section 7.2.2. Cron Schedule should be editted to include more details about Cron Scheduler, as follows:

7.2.2.  Cron Schedule
This schedule type provides scheduling capability based on a Quartz Scheduler CronTrigger expression. The attributes for this schedule type are as follows:

scheduleid
    A unique identifier string for the schedule. Used to reference a schedule from a listener 
cronExpression
    Quartz Scheduler CronTrigger expression
startDate
    The schedule start date and time. The format of this attribute value is that of the XML Schema type "dateTime". See dateTime. 
endDate
    The schedule end date and time. The format of this attribute value is that of the XML Schema type "dateTime". See dateTime. 

Example:

<providers>
	<schedule-provider name="schedule">
		<cron-schedule scheduleid="cron-trigger" cronExpression="1 * * * * ?" />
        </schedule-provider>
</providers>

This example will fire the scheduler every minute, on the 1st second of the minute. You can read more about Quartz Scheduler, CronTriggers here:

http://www.quartz-scheduler.org/docs/tutorials/crontrigger.html