diff --git a/docs/navigation-structure.md b/docs/navigation-structure.md
index a4fef75ef4a46d8e6bd5684652febb99c90f3e74..d6d584445c6885c97440170c86053177888b37b0 100644
--- a/docs/navigation-structure.md
+++ b/docs/navigation-structure.md
@@ -38,6 +38,10 @@ nav_order: 4
 ---
 ```
 
+The specified `nav_order` parameters on a site should be all integers or all strings.
+Pages without a `nav_order` parameter are ordered alphabetically by their `title`,
+and appear after the explicitly-ordered pages at each level.
+
 ---
 
 ## Excluding pages