This attribute is used only when splitting or merging existing topology regions. It specifies which topology regions are in a migration status. A node will only exchange topological information with a connected node under the following conditions: (i) the nodes belong to the same topology region, (ii) one of the nodes is provisioned with the default regionId of 0, (iii) the connected node's splittingRegionIds attribute is provisioned to contain the local node's regionId value and the local node's splittingRegionIds is also provisioned to contain the connected node's regionId value when both two nodes' regionIds are different and non-zero.

When this attribute is used during migration of regions, values for the attribute are normally the old and new regionIds for the node. Use of this attribute makes it possible to migrate existing topology regions in the following cases: (i) splitting a topology region into two without isolating a node, (ii) merging two different topology regions into one without introducing an extra topological barrier.

The attribute should be cleaned when all migration activities are complete. At this point, the region boundary will take effect.