diff --git a/extensions/openpower-pels/extended_user_data.cpp b/extensions/openpower-pels/extended_user_data.cpp
new file mode 100644
index 0000000..0731b60
--- /dev/null
+++ b/extensions/openpower-pels/extended_user_data.cpp
@@ -0,0 +1,131 @@
+/**
+ * Copyright © 2020 IBM Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "extended_user_data.hpp"
+
+#include "pel_types.hpp"
+#ifdef PELTOOL
+#include "user_data_json.hpp"
+#endif
+#include <fmt/format.h>
+
+#include <phosphor-logging/log.hpp>
+
+namespace openpower::pels
+{
+
+using namespace phosphor::logging;
+
+void ExtendedUserData::unflatten(Stream& stream)
+{
+    stream >> _header;
+
+    if (_header.size <= SectionHeader::flattenedSize() + 4)
+    {
+        throw std::out_of_range(
+            fmt::format("ExtendedUserData::unflatten: SectionHeader::size {} "
+                        "too small",
+                        _header.size));
+    }
+
+    size_t dataLength = _header.size - 4 - SectionHeader::flattenedSize();
+    _data.resize(dataLength);
+
+    stream >> _creatorID >> _reserved1B >> _reserved2B >> _data;
+}
+
+void ExtendedUserData::flatten(Stream& stream) const
+{
+    stream << _header << _creatorID << _reserved1B << _reserved2B << _data;
+}
+
+ExtendedUserData::ExtendedUserData(Stream& pel)
+{
+    try
+    {
+        unflatten(pel);
+        validate();
+    }
+    catch (const std::exception& e)
+    {
+        log<level::ERR>(
+            fmt::format("Cannot unflatten ExtendedUserData: {}", e.what())
+                .c_str());
+        _valid = false;
+    }
+}
+
+ExtendedUserData::ExtendedUserData(uint16_t componentID, uint8_t subType,
+                                   uint8_t version, uint8_t creatorID,
+                                   const std::vector<uint8_t>& data)
+{
+    _header.id = static_cast<uint16_t>(SectionID::extUserData);
+    _header.version = version;
+    _header.subType = subType;
+    _header.componentID = componentID;
+
+    _creatorID = creatorID;
+    _reserved1B = 0;
+    _reserved2B = 0;
+    _data = data;
+    _header.size = flattenedSize();
+    _valid = true;
+}
+
+void ExtendedUserData::validate()
+{
+    if (header().id != static_cast<uint16_t>(SectionID::extUserData))
+    {
+        log<level::ERR>(
+            fmt::format("Invalid ExtendedUserData section ID {}", header().id)
+                .c_str());
+        _valid = false;
+    }
+    else
+    {
+        _valid = true;
+    }
+}
+
+std::optional<std::string>
+    ExtendedUserData::getJSON(uint8_t creatorID,
+                              const std::vector<std::string>& plugins) const
+{
+    // Use the creator ID value from the section.
+#ifdef PELTOOL
+    return user_data::getJSON(_header.componentID, _header.subType,
+                              _header.version, _data, _creatorID, plugins);
+#endif
+    return std::nullopt;
+}
+
+bool ExtendedUserData::shrink(size_t newSize)
+{
+    // minimum size is 8B header + 4B of fields + 4B of data
+    if ((newSize < flattenedSize()) &&
+        (newSize >= (Section::flattenedSize() + 8)))
+    {
+        auto dataSize = newSize - Section::flattenedSize() - 4;
+
+        // Ensure it's 4B aligned
+        _data.resize((dataSize / 4) * 4);
+        _header.size = flattenedSize();
+        return true;
+    }
+
+    return false;
+}
+
+} // namespace openpower::pels