All termsProtocols
HL7 SIU
An HL7 v2 scheduling message — broadcasts appointment events (new, modified, cancelled) from a scheduling system.
When to use it
When downstream systems (RIS, reminders, worklists) must track appointment changes.
In plain terms
The shared calendar invite that everyone's system subscribes to.
Common gotchas
- SIU event codes (S12 new, S14 modify, S15 cancel…) drive different actions.
- Not all systems consume SIU; some derive scheduling from ORM instead.
- Time-zone and slot handling cause subtle mismatches.