VOEvent is the root element for describing observations of immediate astronomical events. For more information, see http://www.ivoa.net/twiki/bin/view/IVOA/IvoaVOEvent. The event consists of at most one of each of: Who, What, WhereWhen, How, Why, Citations, Description, and Reference. Who: Curation Metadata Author information follows the IVOA curation information schema: the organization responsible for the packet can have a title, short name or acronym, and a logo. A contact person has a name, email, and phone number. Other contributors can also be noted. What: Event Characterization. This is the part of the data model that is chosen by the Authoer of the event rather than the IVOA. There can be Params, that may be in Groups, and Tables, and simpleTimeSeries. There can also be Description and Reference as with most VOEvent elements. What/Param definition. A Param has name, value, ucd, unit, dataType; and may have Description and Reference. What/Group definition: A group is a collection of Params, with name and type attributes. What/Table definition. This small Table has Fields for the column definitions, and Data to hold the table data, with TR for row and TD for value of a table cell. WhereWhen: Space-Time Coordinates. Lots and lots of elements here, but the import is that each event has these: observatory, coord_system, time, timeError, longitude, latitude, posError. Part of WhereWhen Part of WhereWhen Part of WhereWhen Part of WhereWhen Part of WhereWhen Part of WhereWhen Part of WhereWhen Part of WhereWhen Part of WhereWhen Part of WhereWhen Part of WhereWhen How: Instrument Configuration. Built with some Description and Reference elements. Why: Initial Scientific Assessment. Can make simple Concept/Name/Desc/Ref for the inference or use multiple Inference containers for more semantic sophistication. Why/Inference: A container for a more nuanced expression, including relationships and probability. Citations: Follow-up Observations. This section is a sequence of EventIVORN elements, each of which has the IVORN of a cited event. Citations/EventIVORN. The value is the IVORN of the cited event, the 'cite' attribute is the nature of that relationship, choosing from 'followup', 'supersedes', or 'retraction'. Reference: External Content. The payload is the uri, and the 'type' describes the nature of the data under that uri. The Reference can also be named.