diff --git a/book/source/01-intro.md b/book/source/01-intro.md
index 21402c6..7a3a638 100644
--- a/book/source/01-intro.md
+++ b/book/source/01-intro.md
@@ -46,7 +46,7 @@ This document describes OpenPGP concepts at the "library" level of abstraction,
 
 ## Which version of OpenPGP does this address?
 
-The documentation mainly covers version 6 of OpenPGP, while occasionally noting differences to previous versions that are relevant to application developers.
+This documentation covers all aspects of modern OpenPGP, most of which are common between current and upcoming versions. The basic concepts of OpenPGP are shared between all versions. Where there are differences, we center version 6, while occasionally noting differences to previous versions that are relevant to application developers.
 
 Version 4 of OpenPGP will remain relevant for a number of years;
 some version 3 artifacts are still in use as of this writing.