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diff --git a/src/lib/cc/server_tag.h b/src/lib/cc/server_tag.h
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+// Copyright (C) 2019 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef SERVER_TAG_H
+#define SERVER_TAG_H
+
+#include <string>
+
+namespace isc {
+namespace data {
+
+/// @brief Represents a server tag.
+///
+/// The server tag is a label identifying a server or all servers which
+/// configuration is stored in the database. The label "all" is reserved
+/// and it means "all servers". A configuration object in the database
+/// associated with this server tag belongs to all servers. The server
+/// tag must not be empty, must not be longer than 256 characters
+/// (excluding leading and terminating whitespaces, which are trimmed)
+/// and must not be set to "any" which has a special meaning for the
+/// server selector.
+class ServerTag {
+public:
+
+    /// @brief Server tag for all servers as text.
+    static std::string ALL;
+
+    /// @brief Default constructor.
+    ///
+    /// Creates server tag for all servers.
+    ServerTag();
+
+    /// @brief Constructor.
+    ///
+    /// @param tag server tag provided as string. The tag is converted to
+    /// lower case.
+    explicit ServerTag(const std::string& tag);
+
+    /// @brief Checks if the server tag is set to "all servers".
+    ///
+    /// @return true if the server tag is set to all servers, false
+    /// otherwise.
+    bool amAll() const;
+
+    /// @brief Returns server tag as string.
+    ///
+    /// @return lower case server tag.
+    std::string get() const {
+        return (tag_);
+    }
+
+    /// @brief Overload of the less operator for using @c ServerTag in sets.
+    ///
+    /// @param other other server tag to compare to.
+    /// @return true if this server tag is less than the other server tag.
+    bool operator<(const ServerTag& other) const {
+        return (tag_ < other.tag_);
+    }
+
+private:
+
+    /// @brief Holds server tag as string.
+    std::string tag_;
+};
+
+/// @brief Insert the @c ServerTag as a string into stream.
+///
+/// @param os stream to insert server tag into.
+/// @param server_tag server tag to be converted to text and
+/// inserted into a stream.
+/// @return Reference to the stream object with inserted server
+/// tag.
+std::ostream&
+operator<<(std::ostream& os, const ServerTag& server_tag);
+
+} // end of namespace isc::data
+} // end of namespace isc
+
+#endif // SERVER_TAG_H