Booleans
Boolean fields are either the string 'yes' or the empty string ''.
This may seem odd and wasteful of space. It does allow one to simply
display the string next to a label without translation.
Space is very cheap and getting cheaper all the time.
Dates
Date fields contain 8 digits yyyymmdd.
This allows for easy sorting of records by date.
For internal operations date fields are converted into Date::Simple
objects. See that module's perldoc for details.
We do not store timezone or locale information.
We really don't need the full generality (and massive complexity) of DateTime.
Times
Time fields are stored in 24 hour time hhmm. No seconds.
For internal operations time fields are converted into Time::Simple objects.
See that module's perldoc for details.