VisibilityCone.md

@@ -2,7 +2,7 @@ This page describes the content of a CZML document. Please read [How to get star
 
 # Visibility Cone
 
-**Extends** : [CZMLPrimaryObject](CZMLPrimaryObject)
+**Implements** : [CZMLPrimaryObject](CZMLPrimaryObject)
 
 **Example** : 
 ```json