diff --git a/docs/newgrf-roadstops.html b/docs/newgrf-roadstops.html
index 416df63d43..b0e0226ebf 100644
--- a/docs/newgrf-roadstops.html
+++ b/docs/newgrf-roadstops.html
@@ -400,6 +400,7 @@
1 - North-bound only
2 - South-bound only
3 - No entry
+
The remaining bits are reserved for future use and should be masked.