diff --git a/draft-ietf-rats-reference-interaction-models.md b/draft-ietf-rats-reference-interaction-models.md
index 873259f..21ecb32 100644
--- a/draft-ietf-rats-reference-interaction-models.md
+++ b/draft-ietf-rats-reference-interaction-models.md
@@ -871,7 +871,7 @@ The CHARRA project and all corresponding code and data maintained on GitHub are
 
 ## Implementation Dependencies
 
-The implementation requires the use of the official Trusted Computing Group (TCG) open-source Trusted Software Stack (TSS) for the Trusted Platform Module (TPM) 2.0.
+The implementation requires the use of the Trusted Computing Group (TCG) Trusted Software Stack (TSS), and an HSM interoperable with the Trusted Platform Module Library specifications, e.g., a Trusted Platform Module (TPM) 2.0 or equivalent implementation.
 The corresponding project resources (code and data) for Linux-based operating systems are maintained on GitHub at <https://github.com/tpm2-software/tpm2-tss/>.
 
 The implementation uses the Constrained Application Protocol {{-COAP}} (http://coap.technology/) and the Concise Binary Object Representation {{-CBOR}} (https://cbor.io/).