This is from the variables.h file

Code:
#define ThisPerformance	(g->w)
#define DrawDownMax		g->w.vDrawDown
#define MAE					g->w.vEquityDown
#define MarginMax			g->w.vMarginMax
#define RiskMax			g->w.vRiskMax
#define SpreadCost		g->w.vSpreadCost
#define SlippageCost		(g->w.vSlippageWin+g->w.vSlippageLoss)
#define RollCost			g->w.vRollCost
#define CommissionCost	g->w.vCommissionCost
#define ReturnMean		g->w.vMean
#define ReturnStdDev		g->w.vStdDev
#define Ulcer				g->w.vUlcer
#define R2					g->w.vR2
#define DrawDownBars		g->w.numDrawDownBars
#define DrawDownBarsMax	g->w.numDrawDownMax
#define LossStreakMax	g->w.numLossStreakMax
#define NumOpenMax		g->w.numTradesMax
#define InMarketBars		g->w.numMarketBars
#define InMarketSum		g->w.numMarketTotal

My understanding is that you use for example ThisPerformance.vR2 to get the R2