Having a look through my favorite files from Forex-TSD, this is the Roofing Stochastic by Mladen.

As explained by Mladen:
The roofing Stochastic is a version that uses adaptive smoothing in calculation instead of using fixed length calculation for that. In some cases difference is significant (especially in cases when there is a sudden change in price) so it seems to be better responsive to what the market is doing.