diff --git a/book/source/glossary.md b/book/source/glossary.md
index dc23a57..7ba86b8 100644
--- a/book/source/glossary.md
+++ b/book/source/glossary.md
@@ -174,6 +174,8 @@ Encrypted Data
 Encryption Key Flag
     A {term}`Key Flag`, indicating that a {term}`Component Key` can be used for encrypting data. See [](key-flags).
 
+    There are two distinct encryption key flags, indicating that the key can encrypt communications, or data in long-term storage respectively.
+
 Expiration
     A mechanism by which a {term}`Component` is invalidated due to the {term}`Expiration Time` of its {term}`binding signature` being older than the {term}`Reference Time` by which it is validated.