Definition. Average Spent Output Lifespan (ASOL) is the average age, in days, of spent transaction outputs. MSOL is the median counterpart.

Technical. Computed count-weighted across spent outputs, not weighted by coin volume. Outputs with a lifespan of less than one hour are discarded. For assets other than BTC, the metric uses an account-based approach: spent coins are an address's balance decreases, aged by the address's balance-weighted average acquisition time.