A system for naming days of the year, called calander dates.

A commemorative event is one which commemorates an earlier historical event. For instance, the Trafalgar 200 event commemorated the 200th anniversary of the Battle of Trafalgar.

A week is a period longer than a day and shorter than a month. In most modern societies the week is a period of seven days, each of which is named. This type is used for these named days.

A day of that occures annually according to specific rule such as "The first day of May", or "The Tuesday following the first Monday in November."

The geological time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. While "period" is itself a subdivision of this scale, it is used colloquially in the name of this type to include all subdivisions of the scale.

A holiday is a day set aside for celebration or observance. It usually occurs at a regular time in the calendar, and may be religious or secular. When holidays are grouped together, they may form a holiday period.

This type is used to categorise holidays into groupings such as national holidays, religious holidays, etc.

A group of related holidays that occur together annually.

A month is a unit of time roughly equivalent to the lunar cycle (around 28 days). This type is for named months in any standard calendar, including the Julian calendar, the Islamic calendar, and so on.

A time zone is a region within which the time is always the same. Regions which have the same standard time, but which have different summer (or daylight saving) times, should be treated as different time zones.

This type was designed for recording the uncertainty of geologic dates (in units of millions of years), although it could be used for any other kind of uncertain dating that needs to be expressed in millions of years.