diff --git a/grudge/symbolic/primitives.py b/grudge/symbolic/primitives.py
index 0b9fac20332e505b038ee2ed9bda94485048d8d2..4f50b636aed4af53406add1d7237b73137dec466 100644
--- a/grudge/symbolic/primitives.py
+++ b/grudge/symbolic/primitives.py
@@ -64,6 +64,7 @@ DOF description
 
 .. autoclass:: DTAG_SCALAR
 .. autoclass:: DTAG_VOLUME_ALL
+.. autoclass:: DTAG_BOUNDARY
 .. autoclass:: QTAG_NONE
 .. autoclass:: DOFDesc
 .. data:: DD_SCALAR