Before:
Inconsistent date formats used in different fields for field value comparison, so some comparisons didn't work. Also, some fields had times, some didn't.
After:
All date fields are normalized to Ymd, allowing comparisons to work. Ymd also allows comparisons to be made only on dates, as the field names suggest, rather than datetimes (e.g. we can compare a date to today to see if it is today).
Documentation added.