tlv: rewrite syntax specifications using IETF ABNF

refs #4853

Change-Id: Iad79a63675279d53de2f7bb4891d10bf01d0424f
diff --git a/signed-interest.rst b/signed-interest.rst
index 63ad44b..9043551 100644
--- a/signed-interest.rst
+++ b/signed-interest.rst
@@ -5,22 +5,12 @@
 
 **Signed Interest** is a mechanism to issue an authenticated Interest.
 
-::
+A signed Interest is an Interest where:
 
-    SignedInterest ::= INTEREST-TYPE TLV-LENGTH
-                         Name (must end with ParametersSha256DigestComponent)
-                         CanBePrefix?
-                         MustBeFresh?
-                         ForwardingHint?
-                         Nonce?
-                         InterestLifetime?
-                         HopLimit?
-                         ApplicationParameters
-                         InterestSignatureInfo
-                         InterestSignatureValue
+* Name ends with ``ParametersSha256DigestComponent``.
+* ``InterestSignature`` is present.
 
-
-See :ref:`Interest Signature section <InterestSignature>` for details of ``InterestSignatureInfo`` and ``InterestSignatureValue``.
+See :ref:`Interest Signature section <InterestSignature>` for details on ``InterestSignature``.
 
 Construction of Signed Interest
 -------------------------------
@@ -84,4 +74,4 @@
    Update `s0` to `s` if the signed Interest has been validated according to this and all other rules.
 
   .. note::
-     The first ``SignatureSeqNum`` received is considered valid only if it satisfies the application's policy. For example, application can decide the first ``SeqNum`` can only be a minimum value like 0 or 1, or a value that both sender and receiver agree on.
\ No newline at end of file
+     The first ``SignatureSeqNum`` received is considered valid only if it satisfies the application's policy. For example, application can decide the first ``SeqNum`` can only be a minimum value like 0 or 1, or a value that both sender and receiver agree on.