diff --git a/src/encoding/nfd-constants.hpp b/src/encoding/nfd-constants.hpp
index 8b57def..de19776 100644
--- a/src/encoding/nfd-constants.hpp
+++ b/src/encoding/nfd-constants.hpp
@@ -58,6 +58,7 @@
   LINK_TYPE_NONE           = std::numeric_limits<uint8_t>::max(),
   LINK_TYPE_POINT_TO_POINT = 0, ///< link is point-to-point
   LINK_TYPE_MULTI_ACCESS   = 1, ///< link is multi-access
+  LINK_TYPE_AD_HOC         = 2, ///< link is ad hoc
 };
 
 std::ostream&