Coin-days created
holding time earned by the whole supply
Every bitcoin in existence earns holding time simply by existing. This is how much was earned in this block: the clock ticking for the whole network.
DefinitionCirculating supply at the previous block x the elapsed wall-clock time. Age is real elapsed time off a monotonised block clock (the running maximum of block timestamps), not blocks divided by 144. The ARK and Glassnode papers write this in COINBLOCKS, one block of holding rather than one day; that is the same ledger in a different time unit and is not published separately.