What is the SSN proxy good for? (Invited)

The SSN has now become a reliable proxy with a relatively long database and a good calibration against modern sunspot observations and other proxies. Generally a proxy index of this type serves as a guide to the development of solar magnetic activity. We are interested in this characterization on various time scales: the current proxy data, the new extension through the revised timeseries of sunspot number to the recent past, and the older proxies such as radioisotopes. The tree-ring signatures of radioisotopes in particular have scored a recent breakthrough, via unambiguous detections of flare/SEP activity on thousand-year time scales. It makes physical sense to ask how these proxies relate to some quantitative aspect of solar magnetism, such as a parameter predicted by an accepted dynamo theory. Obviously this is a premature question, but we review here some possibilities in terms of their observables: magnetic flux or Alfvenic Poynting flux, for example.