diff --git a/middle.mkd b/middle.mkd
index f09d85f..373aca2 100644
--- a/middle.mkd
+++ b/middle.mkd
@@ -1058,6 +1058,7 @@ The value of the subpacket type octet may be:
           32   Embedded Signature
           33   Issuer Fingerprint
           34   Preferred AEAD Algorithms
+          35   Intended Recipient Fingerprint
   100 to 110   Private or experimental
 
 An implementation SHOULD ignore any subpacket of a type that it does
@@ -1662,6 +1663,19 @@ signature, the key ID of the Issuer subpacket MUST match the low
 Note that the length N of the fingerprint for a version 4 key is 20
 octets; for a version 5 key N is 32.
 
+#### Intended Recipient Fingerprint
+
+(1 octet key version number, N octets of fingerprint)
+
+The OpenPGP Key fingerprint of the intended recipient primary key.  If
+one or more subpackets of this type are included in a signature, it
+SHOULD be considered valid only in an encrypted context, where the key
+it was encrypted to is one of the indicated primary keys, or one of
+their subkeys.  This can be used to prevent forwarding a signature
+outside of its intended, encrypted context.
+
+Note that the length N of the fingerprint for a version 4 key is 20
+octets; for a version 5 key N is 32.
 
 ### {5.2.4} Computing Signatures