Why it matters
Some older software rejects long or unusual extensions, or non-ASCII characters. That can break sign-up forms or email. A name that works in a browser may fail in a form. This affects how useful a new extension is. Before you adopt a name, test it in forms, email and apps. A common mistake is assuming every system handles new TLDs. The Universal Acceptance Steering Group promotes fixes. Short tests now save support problems later.
Source: icann.org