--- a/include/relpipe/common/text/Iconv.h	Fri Nov 22 15:27:30 2019 +0100
+++ b/include/relpipe/common/text/Iconv.h	Fri Dec 13 14:55:06 2019 +0100
@@ -27,6 +27,8 @@
 #include <ostream>
 #include <sstream>
 
+#include "../type/typedefs.h"
+
 namespace relpipe {
 namespace common {
 namespace text {

--- a/include/relpipe/common/text/TextCodec.h	Fri Nov 22 15:27:30 2019 +0100
+++ b/include/relpipe/common/text/TextCodec.h	Fri Dec 13 14:55:06 2019 +0100
@@ -44,8 +44,8 @@
 	TextCodec();
 	TextCodec(const std::string& encoding);
 	virtual ~TextCodec();
-	std::string fromBytes(std::string bytes);
-	std::string toBytes(std::string text);
+	relpipe::common::type::String fromBytes(std::string bytes);
+	std::string toBytes(relpipe::common::type::String text);
 };
 
 }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/relpipe/common/type/typedefs.h	Fri Dec 13 14:55:06 2019 +0100
@@ -0,0 +1,43 @@
+/**
+ * Relational pipes (library)
+ * Copyright © 2018 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the:
+ *  - GNU Lesser General Public License as published by the Free Software Foundation;
+ *    version 3 of the License or (at your option)
+ *  - GNU General Public License as published by the Free Software Foundation;
+ *    version 2 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/>.
+ */
+#pragma once
+
+#include <cstdint>
+#include <string>
+
+namespace relpipe {
+namespace common {
+namespace type {
+
+// Recommended alias: 
+// namespace t = relpipe::common::type;
+
+using Octet = uint8_t;
+using Integer = int64_t;
+using UnsignedInteger = uint64_t;
+using Boolean = bool;
+/**
+ * Text string as UTF-8 bytes (regardless the current platform encoding).
+ */
+using String = std::string;
+
+}
+}
+}

--- a/include/relpipe/protocol/constants.h	Fri Nov 22 15:27:30 2019 +0100
+++ b/include/relpipe/protocol/constants.h	Fri Dec 13 14:55:06 2019 +0100
@@ -24,6 +24,8 @@
 
 #include "typedefs.h"
 
+// DEPRECATED: this namespace is being moved to common
+
 namespace relpipe {
 namespace protocol {
 

--- a/include/relpipe/protocol/typedefs.h	Fri Nov 22 15:27:30 2019 +0100
+++ b/include/relpipe/protocol/typedefs.h	Fri Dec 13 14:55:06 2019 +0100
@@ -22,6 +22,8 @@
 #include <cstdint>
 #include <string>
 
+// DEPRECATED: this namespace is being moved to common
+
 namespace relpipe {
 namespace protocol {