Name: event-update-request
Type: request
Purpose: >
  Update event attributes
Response: event-update-confirmation
Inherits: message
Elements:
  Signature: { required: true }
  From: { required: true }
  Event-Id: { required: true, type: identifier }
  Event-Data: { required: true, type: object, class: event }
Rejection-Codes:
  31: Sender is not authorized to update event
  41: Event does not exist