diff --git a/core/Constants.hpp b/core/Constants.hpp
index 9d1c5a1c..61d8399a 100644
--- a/core/Constants.hpp
+++ b/core/Constants.hpp
@@ -30,6 +30,7 @@ typedef UInt_t UInteger_t;
 typedef Short_t ShortInt_t;
 typedef Long64_t PdgCode_t;
 
+constexpr double UndefValueDouble = -999.;
 constexpr Floating_t UndefValueFloat = -999.f;
 constexpr ShortInt_t UndefValueShort = -999;
 constexpr Integer_t UndefValueInt = -999;
diff --git a/core/Container.cpp b/core/Container.cpp
index 3a568bb0..be9933b4 100644
--- a/core/Container.cpp
+++ b/core/Container.cpp
@@ -5,6 +5,8 @@
 
 #include "BranchConfig.hpp"
 
+#include <algorithm>
+
 namespace AnalysisTree {
 
 template<>
@@ -32,6 +34,13 @@ void Container::Init(const AnalysisTree::BranchConfig& branch) {
   bools_.resize(branch.GetSize<bool>());
 }
 
+void Container::Reset() {
+  std::fill(doubles_.begin(), doubles_.end(), UndefValueDouble);
+  std::fill(floats_.begin(), floats_.end(), UndefValueFloat);
+  std::fill(ints_.begin(), ints_.end(), UndefValueInt);
+  std::fill(bools_.begin(), bools_.end(), false);
+}
+
 void Container::Print() const noexcept {
   if (!ints_.empty()) {
     std::cout << "Integer fields: ";
diff --git a/core/Container.hpp b/core/Container.hpp
index 6613ffa7..1babd078 100644
--- a/core/Container.hpp
+++ b/core/Container.hpp
@@ -55,6 +55,12 @@ class Container : public IndexedObject {
   }
 
   void Init(const BranchConfig& branch);
+
+  /**
+   * @brief Sets all user-defined fields to undefined values (UndefValueDouble, UndefValueFloat, UndefValueInt, false)
+   */
+  virtual void Reset();
+
   virtual void Print() const noexcept;
 
  protected:
diff --git a/core/EventHeader.cpp b/core/EventHeader.cpp
index a9d431a1..4cffefdd 100644
--- a/core/EventHeader.cpp
+++ b/core/EventHeader.cpp
@@ -17,6 +17,11 @@ void EventHeader::SetVertexPosition3(const TVector3& pos) {
   vtx_pos_[Exyz::kZ] = pos.Pz();
 }
 
+void EventHeader::Reset() {
+  Container::Reset();
+  vtx_pos_.fill(UndefValueFloat);
+}
+
 const EventHeader& EventHeader::GetChannel(size_t i) const {
   if (i == 0) {
     return *this;
diff --git a/core/EventHeader.hpp b/core/EventHeader.hpp
index 09898d42..30082e94 100644
--- a/core/EventHeader.hpp
+++ b/core/EventHeader.hpp
@@ -34,6 +34,11 @@ class EventHeader : public Container {
 
   void SetVertexPosition3(const TVector3& pos);
 
+  /**
+   * @brief Sets vertex position and all user-defined fields to undefined values
+   */
+  void Reset() override;
+
   template<typename T>
   T GetField(Integer_t iField) const {
     if (iField >= 0)