diff --git a/src/data_types.hpp b/src/data_types.hpp
index 1ba0b8a..12d1d6d 100644
--- a/src/data_types.hpp
+++ b/src/data_types.hpp
@@ -21,6 +21,12 @@
 constexpr auto valueIndex = 2;
 constexpr auto metaIndex = 1;
 
+enum class Context
+{
+    START,
+    SIGNAL,
+};
+
 /** @brief A map with references as keys. */
 template <typename Key, typename Value>
 using RefKeyMap = std::map<std::reference_wrapper<Key>, Value, std::less<Key>>;