Name: participant-invalidation
Type: request
Purpose: >
  Prevent the message sender from participating in future votings
Response: participant-invalidation-confirmation
Inherits: message
Elements:
  Signature: required
  From: required
  Event-Id:
    type: identifier
    class: event
Rejection-Codes:
  41: Event does not exist
  42: Event is marked as demo event
  43: Sender is not participant of the event
  44: Participant has already been invalidated
  45: Participant has voted already
  46: Event status does not allow participant invalidations