--- a/src/Doc/System/Environment.thy	Thu May 02 15:40:05 2024 +0200
+++ b/src/Doc/System/Environment.thy	Sun May 12 14:41:13 2024 +0200
@@ -449,7 +449,7 @@
 \<close>
 
 
-section \<open>System registry via TOML\<close>
+section \<open>System registry via TOML \label{sec:system-registry}\<close>
 
 text \<open>
   Tools implemented in Isabelle/Scala may refer to a global registry of