1 files changed, 3 insertions, 0 deletions
diff --git a/txr.1 b/txr.1
index 45f17286..ab75e874 100644
--- a/txr.1
+++ b/txr.1
@@ -16896,6 +16896,9 @@ and
 name a pair of types, such that the left type is a subtype of the right
 type.
 
+If either argument doesn't name a type, the behavior is
+unspecified.
+
 Each type is a subtype of itself. Most other type relationships can be inferred
 from the type hierarchy diagrams given in the introduction to this section.