Universal Acceptance (UA) is a process that ensures that all domain names
and email addresses can be used by all Internet-enabled applications, devices, and systems.
New TLDs are not always recognized by all browsers, mail servers, and hosting platforms. This problem has existed since TLDs expanded beyond [.com] in 2002.
For more information, see https://www.icann.org/resources/pages/universal-acceptance-2012-02-25-en