--- a/mod_rest/res/openapi.yaml	Thu Oct 20 11:28:53 2022 +0100
+++ b/mod_rest/res/openapi.yaml	Mon Oct 24 16:21:59 2022 +0200
@@ -1096,6 +1096,7 @@
       description: Message ID of a message that has been displayed
       xml:
         namespace: urn:xmpp:chat-markers:0
+        x_single_attribute: id
 
     idle_since:
       type: string

--- a/mod_rest/res/schema-xmpp.json	Thu Oct 20 11:28:53 2022 +0100
+++ b/mod_rest/res/schema-xmpp.json	Mon Oct 24 16:21:59 2022 +0200
@@ -733,7 +733,8 @@
                "title" : "XEP-0333: Chat Markers",
                "type" : "string",
                "xml" : {
-                  "namespace" : "urn:xmpp:chat-markers:0"
+                  "namespace" : "urn:xmpp:chat-markers:0",
+                  "x_single_attribute" : "id"
                }
             },
             "encryption" : {