Mention that clients SHOULD follow this guide and document any except…

…ions

proposals/4161-crypto-terminology.md

@@ -53,6 +53,11 @@ example](https://github.com/matrix-org/matrix-spec/pull/1819/files#diff-8b25d378
 When communicating about cryptography with non-technical users, we propose using
 the following terms and concepts.
 
+When referring to concepts outlined in this document in their user interface,
+clients SHOULD use the language specified, except where their own users are
+known to understand different terms more easily. When making such exceptions,
+clients SHOULD document how they deviate from this document, and why.
+
 ### Devices
 
 Instances of a client are called 'devices' (not 'sessions'). Aligned with