You can use these IDs in functions that have a series parameter. 

IMPORTANT

When using series IDs that are revised (a.k.a.PIT SERIES) in a backtest you must use PITSeries() to avoid look-ahead. You can see the effect of not using it in the Fundamental Chart. Try charting the following formulas for Real Gross Domestic Product that calculate the1Y% change:

%(Close(0, ##GNP), Close(3, ##GNP))
%(Close(0, PITSeries(##GNP)), Close(3, PITSeries(##GNP)))

You will notice that using ##GNP without PITSeries() introduces a lot of look-ahead.

Also notice that for 1 Year growth we compare the latest value with the one 3 bars ago since the ##GNP series is updated quarterly.