The datepicker may have a minimum and/or maximum date set to restrict the range of possible dates. These dates may be set as actual dates (new Date(2009, 1 - 1, 26)), as a numeric offset from today (-20), or as a string of periods and units ('+1M +10D'). For the last, use 'D' for days, 'W' for weeks, 'M' for months, or 'Y' for years.