diff --git a/src/H5Format.hpp b/src/H5Format.hpp
index f7024a4..4ad35b5 100644
--- a/src/H5Format.hpp
+++ b/src/H5Format.hpp
@@ -8,6 +8,19 @@
 #include <memory>
 #include <boost/any.hpp>
 
+enum HEADER_DATA_TYPE
+{
+    UINT8,
+    UINT16,
+    UINT32,
+    UINT64,
+    INT8,
+    INT16,
+    INT32,
+    INT64,
+    FLOAT32,
+    FLOAT64
+};
 
 typedef boost::any h5_value;
 
@@ -87,6 +100,8 @@ class H5Format
         virtual const std::map<std::string, DATA_TYPE>& get_input_value_type() const = 0;
         virtual const std::map<std::string, boost::any>& get_default_values() const = 0;
         virtual const h5_group& get_format_definition() const = 0;
+        virtual const std::map<std::string, HEADER_DATA_TYPE>& get_header_value_type() const = 0;
+
         virtual void add_calculated_values(std::map<std::string, boost::any>& values) const = 0;
         virtual void add_input_values(std::map<std::string, boost::any>& values, const std::map<std::string, boost::any>& input_values) const = 0;
         
diff --git a/src/format/NXmxFormat.cpp b/src/format/NXmxFormat.cpp
index a1b52f0..45ae921 100644
--- a/src/format/NXmxFormat.cpp
+++ b/src/format/NXmxFormat.cpp
@@ -14,6 +14,7 @@ class NXmxFormat : public H5Format
     shared_ptr<map<string, DATA_TYPE>> input_value_type = NULL;
     shared_ptr<map<string, boost::any>> default_values = NULL;
     shared_ptr<h5_group> file_format = NULL;
+    shared_ptr<map<string, HEADER_DATA_TYPE>> header_value_type = NULL;
 
     public:
         ~NXmxFormat(){};
@@ -93,6 +94,11 @@ class NXmxFormat : public H5Format
                 {"samz", NX_FLOAT},
             }));
 
+            header_value_type.reset(
+            new map<string, HEADER_DATA_TYPE>({
+                {"pulse_id", UINT64 },
+            }));
+
             // Default values used in the file format.
             default_values.reset(new std::map<string, boost::any>(
             {    
@@ -1056,4 +1062,8 @@ class NXmxFormat : public H5Format
             return *input_value_type;
         }
 
+        const std::map<string, HEADER_DATA_TYPE>& get_header_value_type() const override {
+            return *header_value_type;
+        }
+
 };
\ No newline at end of file