diff --git a/book/source/07-signing_data.md b/book/source/07-signing_data.md
index 88e73b0..2dd56b4 100644
--- a/book/source/07-signing_data.md
+++ b/book/source/07-signing_data.md
@@ -88,6 +88,7 @@ Inline-signed messages enable efficient verification in *one pass*, structured a
 
 Important to note, the signer's public key, critical for the final verification step, is not embedded in the message. Verifiers must acquire this key externally (e.g., from a key server) to authenticate the signature successfully. 
 
+(cleartext-sig)=
 ### Cleartext signatures
 
 The *Cleartext Signature Framework* (CSF) in OpenPGP accomplishes two primary objectives: