Name: lot-invalidation
Type: request
Purpose: >
  Invalidates a lot or a list of lots and prevents the corresponding 
  participants to take part in the votings of the event.
Response: lot-invalidation-confirmation
Inherits: message
Elements:
  Event-Id:
    type: identifier
    class: event
  Lot-Code:
    required: ['Lot-Codes']
    type: string
    min_length: 3
    max_length: 64
  Lot-Codes:
    required: ['Lot-Code']
    type: list
    max_count: 100
    item_type: string
    item_min_length: 3
    item_max_length: 64
Rejection-Codes:
  31: Sender is not authorized to invalidate lots
  41: Event does not exist
  42: Unknown lot code
  43: Lot has alread been invalidated