Procedure:

1. When we bootstrap the system, # successive signatures of every node is 0.
2. For every consensus of txn or micro or final block, if a node signs a signature as ⅔ of nodes included in the co-signature, # successive co-signature is incremented by one.
3. If in any DS epoch, a node fails to submit its PoW solution, then its successive co-signature number will reset to 0.
4. At the beginning of each DS epoch, DS leader will call “CalculateNodePriority” function to calculate the node priority, process the PoW submission and compute sharding structure based on the priority.
5. A DS backup node receives the DS announcement, and also calculates the node priority, and uses it to verify the sharding structure from the announcement.
6. When a new DS leader is selected, the sharding structure is sent to it. The new DS leader can fetch # successive co-signature of each node from the sharding structure.