From parallel waves: On a Form In, those facing in step thru while those facing out Fold behind them. On a Form Out, those facing out do the step thru and those facing in Fold behind them. Form In finishes in double pass thru formation; Form Out finishes in completed double pass thru formation.
Hank Drumm 1975
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.