diff --git a/src/ipips/ipip-0412.md b/src/ipips/ipip-0412.md
index fa0f9e24..9bd8ebeb 100644
--- a/src/ipips/ipip-0412.md
+++ b/src/ipips/ipip-0412.md
@@ -135,9 +135,10 @@ Content-Type: application/vnd.ipld.car;version=1;order=dfs;dups=y
 
 Gateway implementations are free to decide on the implicit default ordering or
 other parameters, and use it in responses when client did not explicitly
-specify, or requested unsupported or unknown query parameter.
+specify any matching preference.
 
-Implementations MAY choose to implement only some of the parameters.
+Implementations MAY choose to implement only some of the parameters and return
+HTTP 406 Not Acceptable when client requested a response with unsupported one.
 
 ## Design rationale