An Event entity, if included in the BetterGedcom model, would record information about an event. Other than the actual type of the event, the three most important properties of an event are when it took place, where it took place, and who were the role players in the event, that is, the persons who took part in the event and the roles they played with respect to the event. Other aspects could include defining any organisation involved in the event, with its role, also any cause (e.g. cause of death) that can be usefully highlighted. It should also be noted that some events (e.g. emigration) could justifiably refer to two locations - the from and to-locations.
As in the case of the Person entity, events can be dealt with at the evidence level, when recording only the information about an event that can be taken from a single item of evidence, or at the conclusion level, where an Event entity represents all the information that a researcher has found out about an event.
Some current physical implementations of
genealogical data (e.g. GEDCOM) place
event information within the most appropriate ("primary") person record. Therefore, a birth event is recorded inside the record of the person who was born, not within the record of the person's father, even if the father were mentioned in the event. Gedcom fortunately has a family record where information about marriage events is placed since duplication would be needed if a marriage event had to be kept in person records also.
However, this physical placement should not be confused with the Logical Data Model that can be derived from GEDCOM, where the most basic rule of data normalisation (removal of repeating attributes) leads to the creation of an Event entity for the Logical Data Model.
Other current models (e.g., Gramps) include the Event entity as a separate entity type in both Logical Data Model and the physical implementation of that model. Information directly about the event is placed in this entity and information about the persons who played roles in the event are placed in Person entities that refer to the Event entity.
Questions being considered about Event entities include:
- Is the Event entity required by the BetterGedcom model in the Logical Data Model? Basic data normalisation says "yes".
- For the physical implementation of the BetterGEDCOM file, is the Gedcom approach adequate (embedding events within persons), or should an approach like Gramps be used (physically separate entities)?
- If BetterGedcom chooses to include the Event entity and also chooses to support the evidence and conclusion aspects of genealogical research, how are the same questions asked of the Person entity to be answered?
- Should Events in BetterGEDCOM apply to multiple persons? (An alternative could be to create a Group entity for this event and apply the Event to the single Group, then trace through the Group to the Persons concerned)
The earlier statement that GEDCOM does not have an entity in its data model is totally wrong. It is impossible to draw a useful logical data model for GEDCOM without having an event entity type.
It is true that events on the physical file in GEDCOM are level 1 and sit inside individuals which are level 0 - but that's about the physical implementation which is not the same thing as the data model.