Merge pull request #2797 from ampproject/avimehta-patch-2

Update amp-var-substitutions.md
ampproject · Apr 4, 2016 · e5c747c · e5c747c
2 parents f3c7dcd + fe6027e
commit e5c747c
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/spec/amp-var-substitutions.md b/spec/amp-var-substitutions.md
@@ -383,7 +383,7 @@ For instance:
 
 Provides the total time the user has been enagaged with the page since the page
 first became visible in the viewport. Total engaged time will be 0 until the
-page first becomes visible.
+page first becomes visible. This variable requires the [amp-analytics](../extensions/amp-analytics/amp-analytics.md) extension to be present on the page.
 
 ## Access