diff --git a/zip-0321.rst b/zip-0321.rst
index 23b3f592..1a7379dd 100644
--- a/zip-0321.rst
+++ b/zip-0321.rst
@@ -132,6 +132,10 @@ Productions of the form ``1*x`` indicate one or more successive instances of the
 production ``x``. Productions of the form ``<n>*<m>x`` indicate at least `<n>` and
 at most `<m>` instances of production ``x``.
 
+Note that this grammar does not allow percent encoding outside the productions
+that use ``qchar``, i.e. the values of label, message, ``reqparam``, and
+``otherparam`` parameters.
+
 Transfer amount
 ---------------
 
@@ -222,6 +226,15 @@ forbidden in ``paramindex``.
 
 Also invalid; duplicate ``amount=`` or ``amount.1=`` fields
 
+::
+
+  zcash:tmEZhbWHTpdKMw5it8YDspUXSMGQyFwovpU?amount=1%30
+  zcash:tmEZhbWHTpdKMw5it8YDspUXSMGQyFwovpU?%61mount=1
+  zcash:%74mEZhbWHTpdKMw5it8YDspUXSMGQyFwovpU?amount=1
+
+Invalid; percent encoding is only allowed in ``qchar`` productions, which do
+not include addresses, amounts, or parameter names.
+
 Forward compatibility
 ---------------------