diff --git a/src/format/NXmxFormat.cpp b/src/format/NXmxFormat.cpp
index 45ae921..a1b52f0 100644
--- a/src/format/NXmxFormat.cpp
+++ b/src/format/NXmxFormat.cpp
@@ -14,7 +14,6 @@ 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(){};
@@ -94,11 +93,6 @@ 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>(
             {    
@@ -1062,8 +1056,4 @@ 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