Cron Expression for Apex Scheduler

Each Cron implementation can have its own variant of the Cron expression (to my surprise) so here is the one used by Force.com.

http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_scheduler.htm

Initially I thought the info was missing the "End Date" part, as that's required by the scheduler UI, but later realized if it's a finite run series specified by the Cron expression, the scheduler knows when to stop.  The UI parameter set on the UI is by design open-ended, so it needs an End Date to limit the run series.