diff --git a/src/engine/documentid.h b/src/engine/documentid.h
new file mode 100644
--- /dev/null
+++ b/src/engine/documentid.h
@@ -0,0 +1,56 @@
+/*
+ * This file is part of the KDE Baloo Project
+ * Copyright 2018  Michael Heidelbach <ottwolt@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef DOCUMENTID_H
+#define DOCUMENTID_H
+
+#include "engine_export.h"
+#include <qglobal.h>
+
+using DeviceId = quint32;
+using Inode = quint32;
+using DeviceIdAndInode = quint64;
+
+namespace Baloo {
+
+class BALOO_ENGINE_EXPORT DocumentId
+{
+public:
+    DocumentId();
+    DocumentId(const DeviceId dev, const Inode ino);
+    DocumentId(const DeviceIdAndInode combinedId);
+    //TODO: DocumentId(const QT_STATBUF& stBuf);
+    ~DocumentId();
+    
+    operator DeviceIdAndInode() const;
+    
+    DocumentId operator=(const DeviceIdAndInode devino);
+    DocumentId operator=(const DocumentId& id);
+    
+    Inode inode();
+    DeviceId deviceId();
+private:
+    DeviceId m_device;
+    Inode m_inode;
+};
+}
+
+#endif // DOCUMENTID_H
diff --git a/src/engine/documentid.cpp b/src/engine/documentid.cpp
new file mode 100644
--- /dev/null
+++ b/src/engine/documentid.cpp
@@ -0,0 +1,113 @@
+/*
+ * This file is part of the KDE Baloo Project
+ * Copyright 2018  Michael Heidelbach <ottwolt@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "documentid.h"
+
+using namespace Baloo;    
+
+DocumentId::DocumentId()
+{
+
+}
+
+DocumentId::DocumentId(const DeviceId dev, const Inode ino)
+    :m_device(dev),
+    m_inode(ino)
+{
+
+}
+
+DocumentId::DocumentId(const DeviceIdAndInode combinedId)
+    : m_device(static_cast<DeviceId>(combinedId >> 4)),
+    m_inode(static_cast<Inode>(combinedId))
+{
+}
+
+    
+DocumentId::~DocumentId()
+{
+
+}
+
+DocumentId DocumentId::operator=(const DocumentId& id)
+{
+    return DocumentId(id.m_device, id.m_inode);
+}
+
+DocumentId DocumentId::operator=(const DeviceIdAndInode devino)
+{
+    return DocumentId(devino);
+}
+
+DocumentId::operator DeviceIdAndInode() const
+{
+    return (m_device << 4) | m_inode;
+}
+
+// FIXME:
+#if(0)
+// Due to operator DeviceIdAndInode(), apparently the following
+// became obsolete.
+
+bool DocumentId::operator==(const DocumentId& other) const
+{
+    return other.m_device == m_device
+    && other.m_inode == m_inode;
+}
+
+bool DocumentId::operator!=(const DocumentId& other) const
+{
+    return other.m_device != m_device
+    || other.m_inode != m_inode;
+}
+
+bool DocumentId::operator==(const DeviceIdAndInode combinedId) const
+{
+    return static_cast<DeviceId>(combinedId >> 4) == m_device
+    && static_cast<Inode>(combinedId >> 4) ==  m_inode;
+}
+
+bool DocumentId::operator!=(const DeviceIdAndInode combinedId) const
+{
+    return static_cast<DeviceId>(combinedId >> 4) != m_device
+    || static_cast<Inode>(combinedId >> 4) !=  m_inode;
+}
+
+bool DocumentId::operator>(const DeviceIdAndInode combinedId) const
+{
+    DeviceId dev = static_cast<DeviceId>(combinedId >> 4);
+    DeviceId ino = static_cast<Inode>(combinedId);
+    return dev > m_device
+    || ( dev == m_device && ino >  m_inode);
+}
+#endif
+
+DeviceId DocumentId::deviceId()
+{
+    return m_device;
+}
+
+Inode DocumentId::inode()
+{
+    return m_inode;
+}
+
+