Represents a monthly schedule. An example of a valid monthly schedule is "on the third Tuesday of the month" or "on the 15th of the month".
One day of the month. 1-31 indicates the 1st to the 31st day. -1 indicates the last day of the month. Months without the target day will be skipped. For example, a schedule to run "every month on the 31st" will not run in February, April, June, etc.
Week day in a month.