$Date{} and $P{} syntax and manipulations in JasperReport Dashboard Designer

In JasperReports Dashboards you can use $Date{...} and $P{...} as values in filters and parameters, dashlets and hyperlinks.

I was wondering if I could go further and retrieve last day of the month from  $Date{...}

or evaluate relative default date MONTH-1 parameter,  $P{MONTH-1} as Date

Any thing re syntax and what could be done with $Date{..} and $P{..} will be really helpful! What other variables could be used in JasperReport Dashboard Designer?

Thank you,

Julia