date_time::gregorian techniques

I have a question about usage. Say i have a date such as using namespace boost::gregorian; date vl_Date_date(2002, Feb, 03); I would like to define a date_period such that the date is within that period. But further I would like this period to cover exactly the month in which the date exists. I had a look at some of the examples etc but could not see a stright forward way of doing this. Is it just me? Also, if i have a date_period object, how do i find out the duration of the period? Thanks for any help, Martin.