diff --git a/D4ParserSax2.cc b/D4ParserSax2.cc
index c9b7647f3..9df34327b 100644
--- a/D4ParserSax2.cc
+++ b/D4ParserSax2.cc
@@ -651,6 +651,9 @@ void D4ParserSax2::dmr_start_element(void *p, const xmlChar *l, const xmlChar *p
         if (parser->check_attribute("dmrVersion"))
             parser->dmr()->set_dmr_version(parser->xml_attrs["dmrVersion"].value);
 
+        if (parser->check_attribute("dap:serialization"))
+            parser->dmr()->set_serialization(parser->xml_attrs["dap:serialization"].value);
+
         if (parser->check_attribute("base"))
             parser->dmr()->set_request_xml_base(parser->xml_attrs["base"].value);
 
diff --git a/DDS.cc b/DDS.cc
index 03e58c37b..71426b969 100644
--- a/DDS.cc
+++ b/DDS.cc
@@ -1257,7 +1257,11 @@ void DDS::print_dmr(ostream &out, bool constrained) {
 
     if (xmlTextWriterWriteAttribute(xml.get_writer(), (const xmlChar *)"dmrVersion",
                                     (const xmlChar *)get_dmr_version().c_str()) < 0)
-        throw InternalErr(__FILE__, __LINE__, "Could not write attribute for dapVersion");
+        throw InternalErr(__FILE__, __LINE__, "Could not write attribute for dmrVersion");
+
+    if (xmlTextWriterWriteAttribute(xml.get_writer(), (const xmlChar *)"dap:serialization",
+                                    (const xmlChar *)get_serialization().c_str()) < 0)
+        throw InternalErr(__FILE__, __LINE__, "Could not write attribute for dap:serialization");
 
     if (!get_request_xml_base().empty()) {
         if (xmlTextWriterWriteAttribute(xml.get_writer(), (const xmlChar *)"xml:base",
diff --git a/DDS.h b/DDS.h
index 35de784d2..6f7ad95f7 100644
--- a/DDS.h
+++ b/DDS.h
@@ -286,6 +286,9 @@ class DDS : public DapObj {
     /** @brief Returns the DAP4 DMR version corresponding to DDS exports. */
     string get_dmr_version() const { return "1.0"; }
 
+    /** @brief Returns the DAP4 data serialization scheme. */
+    string get_serialization() const { return "4.0"; }
+
     /// @deprecated
     void set_dap_major(int p);
     /// @deprecated
diff --git a/DMR.cc b/DMR.cc
index 9337618ac..402b4512b 100644
--- a/DMR.cc
+++ b/DMR.cc
@@ -68,6 +68,7 @@ void DMR::m_duplicate(const DMR &dmr) {
     d_dap_version = dmr.d_dap_version; // String version of the protocol
 
     d_dmr_version = dmr.d_dmr_version;
+    d_serialization = dmr.d_serialization;
 
     d_request_xml_base = dmr.d_request_xml_base;
 
@@ -332,7 +333,11 @@ void DMR::print_dap4(XMLWriter &xml, bool constrained) {
 
     if (xmlTextWriterWriteAttribute(xml.get_writer(), (const xmlChar *)"dmrVersion",
                                     (const xmlChar *)dmr_version().c_str()) < 0)
-        throw InternalErr(__FILE__, __LINE__, "Could not write attribute for dapVersion");
+        throw InternalErr(__FILE__, __LINE__, "Could not write attribute for dmrVersion");
+
+    if (xmlTextWriterWriteAttribute(xml.get_writer(), (const xmlChar *)"dap:serialization",
+                                    (const xmlChar *)serialization().c_str()) < 0)
+        throw InternalErr(__FILE__, __LINE__, "Could not write attribute for dap:serialization");
 
     if (xmlTextWriterWriteAttribute(xml.get_writer(), (const xmlChar *)"name", (const xmlChar *)name().c_str()) < 0)
         throw InternalErr(__FILE__, __LINE__, "Could not write attribute for name");
diff --git a/DMR.h b/DMR.h
index 6464b0daf..1889a0500 100644
--- a/DMR.h
+++ b/DMR.h
@@ -73,8 +73,15 @@ class DMR : public DapObj {
     /// The version of the DMR document
     /// Version 1.0 is the original serialization scheme - Groups were serialized first,
     /// then the top-level variables.
-    /// The 2.0 version indicates the DAP4 Serialization bug fix.
-    std::string d_dmr_version = "2.0";
+    std::string d_dmr_version = "1.0";
+
+    /// The version of the DMR document
+    /// Version 1.0 is the original serialization scheme - Groups were serialized first,
+    /// then the top-level variables.
+    /// When we fixed the DAP4 Serialization bug we added this along
+    /// with a Dataset xml attribute dap:serialization to express this state.
+    /// the original patch changed the d_dmr_version to 2.0 - ndp 4/14/26
+    std::string d_serialization = "4.0";
 
     /// The URL for the request base
     std::string d_request_xml_base;
@@ -179,6 +186,15 @@ class DMR : public DapObj {
      */
     void set_dmr_version(const std::string &v) { d_dmr_version = v; }
 
+    /** @brief Returns the DAP4 serialization that the source service will deliver. */
+    std::string serialization() const { return d_serialization; }
+
+    /**
+     * @brief Sets the DMR document version string.
+     * @param v DMR version value.
+     */
+    void set_serialization(const std::string &v) { d_serialization = v; }
+
     /// Get the URL that will return this DMR
     std::string request_xml_base() const { return d_request_xml_base; }