google:

[1] Extended Contact Attributes - Google Talk for Developers - Google Code (2011-11-16 21:35:51 +09:00 版) <http://code.google.com/intl/ja/apis/talk/jep_extensions/roster_attributes.html>

[2]

xmlns:gr='google:roster'

[3] Forrest はGoogle 検索の意味で使っています。

[4] Sitelinks Search Box | Structured Data | Google Developers (2015-08-13 09:09:54 +09:00 版) <https://developers.google.com/structured-data/slsb-overview>

To tell Google not to show a Sitelinks search box when your site appears in the search results, add the following meta tag to your homepage:
<meta name="google" content="nositelinkssearchbox" />

[5] Firebase Cloud Messaging サーバーについて | Firebase ( (2017-02-24 05:39:30 +09:00)) <https://firebase.google.com/docs/cloud-messaging/server>

次に、送信後同期メッセージの単純な XMPP スタンザを示します。
<message id="">
<gcm xmlns="google:mobile:data">