diff --git a/src/include/ipxe/tls.h b/src/include/ipxe/tls.h
index 51ca02db7..ba5d549dd 100644
--- a/src/include/ipxe/tls.h
+++ b/src/include/ipxe/tls.h
@@ -413,15 +413,15 @@ struct tls_rx {
 	struct io_buffer iobuf;
 	/** List of received data buffers */
 	struct list_head data;
-	/** Received handshake fragment */
+	/** Received handshake fragment (if any) */
 	struct io_buffer *handshake;
 };
 
 /** TLS client state */
 struct tls_client {
-	/** Private key (if used) */
+	/** Private key */
 	struct private_key *key;
-	/** Certificate chain (if used) */
+	/** Certificate chain (if any) */
 	struct x509_chain *chain;
 	/** Security negotiation pending operation */
 	struct pending_operation negotiation;
@@ -431,7 +431,7 @@ struct tls_client {
 struct tls_server {
 	/** Root of trust */
 	struct x509_root *root;
-	/** Certificate chain */
+	/** Certificate chain (if any) */
 	struct x509_chain *chain;
 	/** Certificate validator */
 	struct interface validator;
diff --git a/src/net/tls.c b/src/net/tls.c
index 65d70cf58..3d4280ca9 100644
--- a/src/net/tls.c
+++ b/src/net/tls.c
@@ -2892,6 +2892,27 @@ static int tls_new_finished ( struct tls_connection *tls,
  * @v tls		TLS connection
  * @v iobuf		I/O buffer
  * @ret rc		Return status code
+ *
+ * Following the general robustness principle, we accept handshake
+ * records in any order of arrival and rely on the secure channel
+ * abstraction to determine whether or not the resulting sequence of
+ * operations is sufficient to establish the channel.
+ *
+ * Most non-standard handshake record sequences would not manage to
+ * successfully establish the channel.  For example: a premature
+ * Finished that attempts to skip the ServerKeyExchange would fail
+ * because the channel will reject an attempt to confirm an unbound
+ * peer identity.
+ *
+ * It would be possible for an inventive server to construct
+ * non-standard sequences of handshake records that do successfully
+ * establish the secure channel.  For example: a server could choose
+ * to send a second ServerKeyExchange record with a second valid
+ * signature (over the updated transcript digest that includes the
+ * first ServerKeyExchange).  This would be non-standard and rather
+ * pointless, but would be accepted for the purpose of establishing
+ * the secure channel since it does in fact provide the required
+ * security properties.
  */
 static int tls_new_handshake ( struct tls_connection *tls,
 			       struct io_buffer *iobuf ) {