To add to Toofuzzy's comment, the vWave can also be used by those in retirement years as a indicator of how much might reasonably be drawn from the AIM for spending. Recent diversified portfolio vWave value of 25% cash reserve being indicated for instance, and if your actual cash is 30% then draw the surplus 5% and drop that into whatever interest paying cash account you might use to make cash withdrawals from.
A low SWR, say 2% provides a steady/stable source of income production with relatively low risk. With SWR such as 2% you draw 2% of the portfolio value at the start, and then uplift that amount by inflation as the amount drawn in subsequent years - so a consistent inflation adjusted income is provided. Top slicing additional amounts such as above to supplement that bolsters the total amount of income being drawn/spent i.e. 2% SWR might be enough to cover basic living expenses that are supplemented with additional cash periodically being added from AIM selling shares to levels that exceed the amount (percentage) indicated by the vWave.
AIM is pretty good at throwing off 'surplus' cash, albeit not in a regular manner (at appropriate times after stocks had performed relatively well).
vWave as other have said is also a reasonable indicator of what level of cash reserve to start a new AIM with today i.e. 25% for a diversified AIM.
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