$date(string,format)

$date(string,format) returns a date object defined by the string, parsed according to the given format

For example:

$date(09/11/2001,MM/dd/yyyy)

The idea is to return a specific date to compare against other dates; for example:

<simple-filter field="${order date}"
               relop="GE"
               value="$date(6/1/2009,MM/dd/yyyy)"/
>

where the type of {order date} is date.