Representing inexact historic dates

I'm not sure if this is a feature or support request.

I work with humanities researchers and deal with a lot of dates represented in inexact terms. Sometimes they are centuries, quarter centuries, decades, year range, etc.

With dates2, I can now represent historic dates more easily, but I am still unable to have one field handle several levels of granularity. For instance, some nodes will a precision to the day, other to the year, others to the century. When I try and enter a year range with a granularity of y-m-d, the dates are stored with a seemingly random value.

The work around seems to be using the a precise date range to represent an unknown period. So to represent a century, you'd enter say 1800-jan-01 to 1899-jan-31. Is it possible to allow some date fields to be blank?

Circa dates can also not currently be expressed. It occurs frequently that only one date of a range is known, such as an unknown birth date, but known death date. Would a checkbox to represent a 'circa' date be implemented?

Any comments are appreciated.

Cheers