A mapping that stores the downward message queue MQC head for each para.
Each link in this chain has a form: (prev_head, B, H(M)), where
(prev_head, B, H(M))
prev_head
B
H(M)
A mapping that stores the downward message queue MQC head for each para.
Each link in this chain has a form:
(prev_head, B, H(M)), whereprev_head: is the previous head hash or zero if none.B: is the relay-chain block number in which a message was appended.H(M): is the hash of the message being appended.