I run into this all the time in genealogy. The date object in Gramps, for example, has to support lots of uncertainty, as well as time spans with uncertainty on

I run into this all the time in genealogy. The date object in Gramps, for example, has to support lots of uncertainty, as well as time spans with uncertainty on either end ("He joined the army in March 1968 (unknown day), and left sometime after 1971 but probably before 1974 when he got a job at ABC Corp."). Throw in different calendar systems and you can have a mess. It's one of the things that people think is simple, but really isn't.