1 files changed, 27 insertions, 15 deletions
diff --git a/design-documents/006-extensions.rst b/design-documents/006-extensions.rst
index ee3a287a..6c5a42df 100644
--- a/design-documents/006-extensions.rst
+++ b/design-documents/006-extensions.rst
@@ -49,12 +49,6 @@ The exchange will add two new REQUIRED fields in response to ``/keys``:
 #. The field ``extensions_sig`` that contains the EdDSA signature of the SHA256-hash
    of the normalized JSON-string of the ``extenstions`` object.
 
-The names of extensions MUST be unique and SHOULD include a version information
-in Taler's `protocol version ranges notation`_ as suffix starting with letter
-'``v``', f.e.: ``age_restriction.v1`` or ``p2p.v1:2:3``.
-
-.. _protocol version ranges notation: https://docs.taler.net/core/api-common.html#protocol-version-ranges
-
 
 The necessary changes to ``ExchangeKeysResponse`` are highlighted here:
 
@@ -79,22 +73,40 @@ The necessary changes to ``ExchangeKeysResponse`` are highlighted here:
    }
 
 
+Extension names
+---------------
+
+The names of extensions MUST be unique and SHOULD include a version information
+in Taler's `protocol version ranges notation`_ as suffix starting with letter
+'``v``', f.e.: ``age_restriction.v1`` or ``p2p.v1:2:3``.
+
+.. _protocol version ranges notation: https://docs.taler.net/core/api-common.html#protocol-version-ranges
+
+The full name MUST be registered with GANA_ along with a full description of
+the extension. (TODO: be more specific)
+
+.. _GANA: https://git.gnunet.org/gana.git
+
 The definition of ``Extension`` object itself is mostly up to the particular
-feature.  However, it MUST contain the following fields:
+feature.  **However**, it MUST contain the boolean field ``critical`` that has
+the same semantics as as "critical" has for extensions in X.509_: if true, the
+client must "understand" the extension before proceeding, if "false" clients
+can safely skip extensions they do not understand.
 
-* ``description`` ― a short description of the feature itself.  Can be used by wallets to display information about the feature to the customer.
+.. _X.509: https://datatracker.ietf.org/doc/html/rfc5280#section-4.2
 
-*  ``required`` ― a boolean that indicates if this feature MUST be supported by the wallets and/or merchants in order to use this exchange.
+
+Extension object
+----------------
 
 .. ts:def:: Extension
 
    interface Extension {
-     // Short description of the feature.
-     description: string;
-
-     // Set to ``true`` if this extension MUST be supported by wallets and/or
-     // merchants.
-     required: boolean;
+     // Same semantics as "critical" for extensions in X.509, see
+     // https://datatracker.ietf.org/doc/html/rfc5280#section-4.2.
+     // If "true", the client must "understand" the extension before proceeding.
+     // If "false", clients can safely skip extensions they do not understand.
+     critical: boolean;
 
      // Additional fields defined by the feature itself
      ...