[WARN-A001] - No package description in UML model Event is most often biostratigraphic, e.g. "First appearance of conodont X", but sometimes a paleomagnetic reversal, a chemostratigraphic, cyclostratigraphic or astrochronological event. It is a description of an event hypothsized to be demonstrated at the GSSP Point (Golden Spike). Note that since the Point is the ultimate reference object, the *Event*, rather than the *Point*, must be changed if evidence related to the original "event" is found on the wrong side of the Point. This constrast with an"event-chronologic" approach, by which the event would be defined first, so the position of the Point would have to be adjusted as a consequence of new evidence. The set of all strata on earth that were formed during the related Era