Issuance
new bitcoin minted in this block
How many brand new bitcoin were created in this block. It halves every 210,000 blocks and is the only way coins ever come into existence.
DefinitionThe realised block subsidy actually claimed by the miner, which is not always the full subsidy the rules allowed.
LimitAt least 1,030 blocks claimed less than allowed, including one that claimed nothing at all, so this sits slightly below the halving schedule. That gap is the point of charting both.