What are ITSM's six message types?

• Incident — an event disrupting normal operations / degrading service quality.
• Problem — the unknown cause of one or more incidents.
• Service request — a specific service ask (password change, unlock).
• Service order — ordering items/services from the service catalog.
• Knowledge warehouse article — a captured solution for future speed.
• Operations task — managing recurring tasks.

('Message' isn't a real document type — it's a generic term for any ITSM document type.)