diff --git a/sbnanaobj/StandardRecord/SRTrkChi2PID.cxx b/sbnanaobj/StandardRecord/SRTrkChi2PID.cxx
index 4393be0..5bb50c5 100644
--- a/sbnanaobj/StandardRecord/SRTrkChi2PID.cxx
+++ b/sbnanaobj/StandardRecord/SRTrkChi2PID.cxx
@@ -1,38 +1,20 @@
-////////////////////////////////////////////////////////////////////////
-// \file    SRTrkChi2PID.cxx
-// \brief   An SRTrkChi2PID is a high level track ParticlePID object for
-//          for larana Chi2ParticleID results. 
-////////////////////////////////////////////////////////////////////////
+/**
+ * @file    SRTrkChi2PID.cxx
+ * @brief   An SRTrkChi2PID is a high level track `anab::ParticlePID` object
+ *          for larana `pid::Chi2ParticleID` results. 
+ * @see     SRTrkChi2PID.h
+ */
 
 #include "sbnanaobj/StandardRecord/SRTrkChi2PID.h"
 
-#include <limits>
-
-namespace caf
+void caf::SRTrkChi2PID::setDefault()
 {
+  pdg           = -5;
+  pid_ndof      = -5;
+  chi2_muon     = -5.0;
+  chi2_pion     = -5.0;
+  chi2_kaon     = -5.0;
+  chi2_proton   = -5.0;
+  pida          = -5;
+}
 
-  SRTrkChi2PID::SRTrkChi2PID():
-    pdg(-999),
-    pid_ndof(-99),
-    chi2_muon(std::numeric_limits<float>::signaling_NaN()),
-    chi2_pion(std::numeric_limits<float>::signaling_NaN()),
-    chi2_kaon(std::numeric_limits<float>::signaling_NaN()),
-    chi2_proton(std::numeric_limits<float>::signaling_NaN()),
-    pida(std::numeric_limits<float>::signaling_NaN())
-  {  }
-
-  SRTrkChi2PID::~SRTrkChi2PID(){  }
-
-  void SRTrkChi2PID::setDefault()
-  {
-    pdg           = -5;
-    pid_ndof      = -5;
-    chi2_muon     = -5.0;
-    chi2_pion     = -5.0;
-    chi2_kaon     = -5.0;
-    chi2_proton   = -5.0;
-    pida          = -5;
-  }
-
-} // end namespace caf
-////////////////////////////////////////////////////////////////////////
diff --git a/sbnanaobj/StandardRecord/SRTrkChi2PID.h b/sbnanaobj/StandardRecord/SRTrkChi2PID.h
index bf17ba2..c9dc0d6 100644
--- a/sbnanaobj/StandardRecord/SRTrkChi2PID.h
+++ b/sbnanaobj/StandardRecord/SRTrkChi2PID.h
@@ -1,27 +1,29 @@
-////////////////////////////////////////////////////////////////////////
-// \file    SRTrkChi2PID.h
-////////////////////////////////////////////////////////////////////////
+/**
+ * @file    SRTrkChi2PID.h
+ * @brief   An SRTrkChi2PID is a high level track `anab::ParticlePID` object
+ *          for larana `pid::Chi2ParticleID` results. 
+ * @see     SRTrkChi2PID.cxx
+ */
+
 #ifndef SRTRKCHI2PID_H
 #define SRTRKCHI2PID_H
 
+#include "sbnanaobj/StandardRecord/SRConstants.h"
+
 namespace caf
 {
-  /// Track PID from dE/dx v. residual range Chi2
-  class SRTrkChi2PID
+  /// Track PID from dE/dx v. residual range &chi;&sup2;.
+  struct SRTrkChi2PID
     {
-    public:
-
-      SRTrkChi2PID();
-      virtual ~SRTrkChi2PID();
 
-      int            pdg;          ///< Min Chi2 pdg   
-      int            pid_ndof;    ///< Number of degress of freedom in Chi2 PID fit 
-      float          chi2_muon;   ///< dE/dx v. residual range Chi2 (muon hypothesis)
-      float          chi2_pion;   ///< dE/dx v. residual range Chi2 (pion hypothesis)
-      float          chi2_kaon;   ///< dE/dx v. residual range Chi2 (kaon hypothesis)
-      float          chi2_proton; ///< dE/dx v. residual range Chi2 (proton hypothesis)
+      int            pdg          = -999;                 ///< PDG ID of the lowest Chi2.
+      int            pid_ndof     =  -99;                 ///< Number of degrees of freedom in Chi2 PID fit.
+      float          chi2_muon    = caf::kSignalingNaN;   ///< dE/dx v. residual range Chi2 (muon hypothesis).
+      float          chi2_pion    = caf::kSignalingNaN;   ///< dE/dx v. residual range Chi2 (pion hypothesis).
+      float          chi2_kaon    = caf::kSignalingNaN;   ///< dE/dx v. residual range Chi2 (kaon hypothesis).
+      float          chi2_proton  = caf::kSignalingNaN;   ///< dE/dx v. residual range Chi2 (proton hypothesis).
 
-      float          pida;        ///< PIDA
+      float          pida         = caf::kSignalingNaN;   ///< Particle identification algorithm result (PIDA).
 
       void setDefault();
     };
@@ -29,4 +31,3 @@ namespace caf
 } // end namespace
 
 #endif // SRTRKCHI2PID_H
-//////////////////////////////////////////////////////////////////////////////