There are some new experimental features that have been added in May 16 2019 build
A walk forward can now be run in reverse order.
This is the RunsOOSBkwd feature.
The left graph is a normal WF. The right one the In Sample period has been reversed.
RunsIsFullPeriod uses in sample a little different from the default Runs OOS.
The in sample period is simply x% (30% shown) if the total period.
The reason RunsIsFullperiod was made was to overcome the situation below where clusters are prone to fail.
RunsIS is likely to be removed.