Update draft-ietf-uta-tls13-iot-profile.md

draft-ietf-uta-tls13-iot-profile.md

@@ -616,7 +616,7 @@ This section outlines the requirements for end entity certificates.
 ### Subject
 
 {{!RFC9525, Section 2}} mandates that the subject field not be used to identify a service.
-For IoT purposes, an empty subject field avoids significant confusion for End Entity certificates.
+However, certain IoT applications (for example, {{?I-D.ietf-anima-constrained-voucher}}, {{8021AR}}) use the subject field to encode the device serial number.
 
 The requirement in {{Section 4.4.2 of !RFC7925}} to only use EUI-64 for end
 entity certificates as a subject field is lifted.