diff --git a/book/source/08-signature_internals.md b/book/source/08-signature_internals.md
index bd2337c..29658bc 100644
--- a/book/source/08-signature_internals.md
+++ b/book/source/08-signature_internals.md
@@ -4,4 +4,8 @@
   - Subpackets and how to make sense of them
   - "Negotiating" signature hash algorithm based on recipients preference subpackets
   - Explore viability of having multiple signatures, e.g. v4+v6?
-```
\ No newline at end of file
+```
+
+## Notations
+
+## Zooming in: Package structure