diff --git a/emper/CallerEnvironment.cpp b/emper/CallerEnvironment.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..559b7cbcb781ae5facd0c71b532309c80a727a16
--- /dev/null
+++ b/emper/CallerEnvironment.cpp
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+// Copyright © 2021 Florian Fischer
+#include "CallerEnvironment.hpp"
+
+#include <iostream>
+
+#include "Common.hpp"
+
+auto operator<<(std::ostream& os, const CallerEnvironment& callerEnvironment) -> std::ostream& {
+	switch (callerEnvironment) {
+		case OWNER:
+			return os << "OWNER";
+		case EMPER:
+			return os << "EMPER";
+		case ANYWHERE:
+			return os << "ANYWHERE";
+		default:
+			DIE_MSG("Unknown CallerEnvironment");
+	}
+}
diff --git a/emper/CallerEnvironment.hpp b/emper/CallerEnvironment.hpp
index b06fb4198e0a97a1f46fecc54e21e4e8a48d89d3..8ba325f1a091c3953da998c08617358a0dff831b 100644
--- a/emper/CallerEnvironment.hpp
+++ b/emper/CallerEnvironment.hpp
@@ -1,8 +1,14 @@
 // SPDX-License-Identifier: LGPL-3.0-or-later
-// Copyright © 2020 Florian Schmaus
+// Copyright © 2020-2021 Florian Schmaus, Florian Fischer
 #pragma once
 
+#include <iostream>
+
+/*! Enum representing the different environments where code can be executed */
 enum CallerEnvironment {
-	EMPER,
-	ANYWHERE,
+	OWNER,		/*!< indicate code executed by the worker owning the object */
+	EMPER,		/*!< indicate code executed by any worker */
+	ANYWHERE, /*!< indicate code executed outside of any worker */
 };
+
+auto operator<<(std::ostream& os, const CallerEnvironment& callerEnvironment) -> std::ostream&;
diff --git a/emper/meson.build b/emper/meson.build
index 1faa562936f56b65f0cd8dfab4f5e1900bf1f1ce..fbd3e44cf19c0aa528233b53d914ddc6767c8ee4 100644
--- a/emper/meson.build
+++ b/emper/meson.build
@@ -13,6 +13,7 @@ nasm_gen = generator(nasm,
 emper_asm_objects = nasm_gen.process(emper_asm_sources)
 
 emper_cpp_sources = [
+  'CallerEnvironment.cpp',
   'Runtime.cpp',
   'Emper.cpp',
   'Fiber.cpp',