diff --git a/Filter-syntax-extensions.md b/Filter-syntax-extensions.md
index d86fb41..bbd796f 100644
--- a/Filter-syntax-extensions.md
+++ b/Filter-syntax-extensions.md
@@ -1,5 +1,11 @@
 µBlock supports most of [Adblock Plus filter syntax](https://adblockplus.org/en/filter-cheatsheet). However µBlock does not support some very specific case, and also added its own extensions to ABP filter syntax.
 
+### Not supported		
+
+`document`:
+
+Not supported. The purpose of the `document` option is to disable µBlock completely. The reason it is not supported is to be sure that users explicitly disable µBlock themselves if they wish (through [whitelisting](https://github.com/gorhill/uBlock/wiki/How-to-whitelist-a-web-site)), not having some external filter list decide for them.
+
 ### Extended syntax
 
 µBlock extends Adblock Plus filter syntax.