MSOL shows the median age of outputs spent on a given day. Half of spent outputs were younger than this level and half were older, so it describes the midpoint of the spent-age distribution rather than its average.
A rising series means older supply has moved into the center of the day’s spent set. A low or flat reading means typical spent outputs are still relatively young. It is most useful with ASOL and Spent Volume Age Bands, where the question is broad old-coin participation versus a thinner old-output tail.
The key distinction is robustness. MSOL is much less sensitive than ASOL to a small number of very old spent outputs, so it is cleaner for typical spent-output age but less expressive about extremes on its own.
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