diff --git a/hoot-core/src/main/cpp/hoot/core/conflate/network/NetworkDetails.h b/hoot-core/src/main/cpp/hoot/core/conflate/network/NetworkDetails.h
index 35a11dd..0a68c6a 100644
--- a/hoot-core/src/main/cpp/hoot/core/conflate/network/NetworkDetails.h
+++ b/hoot-core/src/main/cpp/hoot/core/conflate/network/NetworkDetails.h
@@ -74,6 +74,9 @@ public:
Radians calculateHeading(ConstEdgeLocationPtr el) const;
+ /**
+ * Callers to this method are responsible for filtering out invalid edges.
+ */
Radians calculateHeadingAtVertex(ConstNetworkEdgePtr e, ConstNetworkVertexPtr v) const;
QList<EdgeSublineMatchPtr> calculateMatchingSublines(ConstNetworkEdgePtr e1,