---
title: Matter Constants
framework: matter
role: collectionGroup
role_heading: API Collection
path: matter/matter-constants
---

# Matter Constants

## Topics

### Constants

- [MTRDataVersionKey](matter/mtrdataversionkey.md)
- [MTREventIsHistoricalKey](matter/mtreventishistoricalkey.md)
- [MTRPreviousDataKey](matter/mtrpreviousdatakey.md)
- [MTR_ENABLE_PROVISIONAL](matter/mtr_enable_provisional.md)
- [MTR_ENABLE_UNSTABLE_API](matter/mtr_enable_unstable_api.md)
- [MTR_NO_AVAILABILITY](matter/mtr_no_availability.md)