Schedule rules set a variable or output to a selected value on a defined schedule for a period of time when a specified condition is met. For instance:
Set Coffee Maker to TRUE in month(s) [JFMAM---SOND] day(s) [-MTWTF-] at hours(s) [------6-----------------] and  minutes
for 45 minutes when Vacation is not true
NOTE: A schedule rule includes the length of time that the rule will be active when triggered. It's more comprehensive than "Turn outside lights on at 10:00". Instead, it's "Turn outside lights on at 10:00 for 8 hours".
Variable Or Output
Schedule rules can set any variable (analog or state variable) or any output (analog or discrete). This example rule is setting a discrete output that turns on the coffee maker.
Schedule rules set the chosen output or variable to a value - in this case TRUE.
This term is the most complex. You can specify 'all months' or you may choose individual months.
In the same way, you can specify all days of the month, specific days of the month, or specific days of the week.
Finally, you can select every hour or specific hours, and you can select one or more minutes during the hour. The selected hours are shown in condensed form in a bracketed list with 24 positions starting at Midnight. Midnight and Noon are shown as 'M' and 'N'. 10:00 and 11:00 are shown as 'T' and 'E'. The example below shows a rule that's triggered at Midnight, 8:00AM, 10:00AM, Noon, and 5:00PM.
In this example, the rule will trigger in January through May and September through December. During those months it will trigger on weekdays (MTWTF, Monday through Friday). On the days when it triggers, it will do so at 6:15.
Period of Time
Schedule rules always set the selected variable or output for a period of time - in this case 45 minutes. the period is a numeric value, and the units can be minutes, hours, days, weeks, or months. If months are chosen, the actual period is calculated as months times 30 days.
Finally, schedule rules are active only when a specified condition is met. In this case, there's a state variable called vacation, and the rule is only active when vacation is not true.