interest+data: forbid unrecognized non-critical TLV before/inside Name
refs #4587
Change-Id: I58d0a402b8b1339eb8c301141a186d04419862aa
diff --git a/data.rst b/data.rst
index eba092c..7444730 100644
--- a/data.rst
+++ b/data.rst
@@ -13,6 +13,9 @@
The Data packet represents some arbitrary binary data (held in the optional ``Content`` element) together with its ``Name``, some additional bits of optional information (``MetaInfo``), and a digital ``Signature`` of the other element(s). The Name is the first element since all NDN packet processing starts with the name. Signature is put at the end of the packet to ease the implementation because signature computation covers all the elements before Signature.
+As recommended by :ref:`TLV evolvability guidelines <evolvability>`, unrecognized non-critical TLV elements may appear in the Data packet.
+However, they must not appear before the ``Name`` element.
+
Name
~~~~
diff --git a/interest.rst b/interest.rst
index 8218007..caa6ba3 100644
--- a/interest.rst
+++ b/interest.rst
@@ -22,6 +22,9 @@
``CanBePrefix``, ``MustBeFresh``, ``InterestLifetime``, and ``ForwardingHint`` are optional elements to guide Interest matching or forwarding.
Interest can also include an optional ``Parameters`` element.
+As recommended by :ref:`TLV evolvability guidelines <evolvability>`, unrecognized non-critical TLV elements may appear in the Interest packet.
+However, they must not appear before the ``Name`` element.
+
Name
~~~~
diff --git a/name.rst b/name.rst
index d0c4e00..8fad777 100644
--- a/name.rst
+++ b/name.rst
@@ -39,6 +39,7 @@
TLV-TYPE of name component MUST be in the range ``1-65535`` (inclusive).
``Name`` element containing a sub-element out of this range is invalid and the packet SHOULD be dropped.
+This requirement overrides the TLV evolvability guidelines.
Name component with TLV-TYPE ``0`` (zero) is reserved to indicate an invalid name component.
diff --git a/tlv.rst b/tlv.rst
index 9b0233a..5741ea1 100644
--- a/tlv.rst
+++ b/tlv.rst
@@ -126,6 +126,8 @@
65535 => TT02FFFF
65536 => TT0400010000
+.. _evolvability:
+
Considerations for Evolvability of TLV-Based Encoding
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~