[Boost-users] Boost.Date_Time and quarters, incomplete (or unknown) dates

Is there special support in Boost.Date_Time to support quarters, or (just) years? Consider the following scenario: I have a customer (or patient) whose (exact) date of birth is not known, only that 'he was born in 1960' or in 'May 1960' (w/o attached information on month or days). Is there another way to handle this (and preserve knowledge about the incomplete information) besides pretending that month (and perhaps even day) is 1 and storing additional flags about the information being not actually present? Best regards Christoph