An array of Material CRC and instance id pairs generated by RayTracingAccelerationStructure.CullInstances when using RayTracingInstanceCullingFlags.ComputeMaterialsCRC flag.
The array can be used for example to compute a composite CRC of all Materials and reset the convergence during path tracing if the user changed a Material property or Materials used in path tracing were created or deleted.
Additional resources: Material.ComputeCRC, HashUtilities.