diff --git a/book/source/04-certificates.md b/book/source/04-certificates.md
index fe9ab64..f8c6c5e 100644
--- a/book/source/04-certificates.md
+++ b/book/source/04-certificates.md
@@ -283,6 +283,7 @@ The popular [SKS keyserver network experienced certificate flooding firsthand](h
 This section only contains notes and still needs to be written
 ```
 
+(append-only)=
 ### Certificate management / Evolution of a certificate over time
 
 Minimized versions, merging, effective "append only" semantics, ...