add instructions for older software

AnalysisHowTo/PIDstudy/DSelector_p2gamma.C

@@ -206,7 +206,7 @@ Bool_t DSelector_p2gamma::Process(Long64_t locEntry)
                 TLorentzVector locMissingP4_OffProton = locBeamP4_Measured + dTargetP4;
                 locMissingP4_OffProton -= locProtonP4_Measured;
 
-		/******************************************** EXECUTE NON-PID CUTS **********************************************/
+		/******************************************** EXECUTE YOUR NON-PID SELECTION CUTS HERE **********************************************/
 
 		/**************************************** PreSelection ******************************************/
 		//The space-time information when the photons hit the detector                
@@ -287,7 +287,11 @@ Bool_t DSelector_p2gamma::Process(Long64_t locEntry)
 		/******************************************** EXECUTE ANALYSIS ACTIONS *******************************************/
 
 		// Loop through the analysis actions, executing them in order for the active particle combo
-		dAnalyzeCutActions->Perform_ActionWeight(locHistAccidWeightFactor); // Must be executed before Execute_Actions()
+		dAnalyzeCutActions->Perform_ActionWeight(locHistAccidWeightFactor); 
+
+		// Note: Using accidental subtraction in AnalyzeCutAction requires version > 1.9.0 of gluex_root_analysis. To use without accidental subtraction and a previous version of the software, comment out the line above and uncomment next line
+		//dAnalyzeCutActions->Perform_Action();
+
 		if(!Execute_Actions()) //if the active combo fails a cut, IsComboCutFlag automatically set
 			continue;