Emoji domain names have received some press over that last year thanks, in part, to .ws allowing registrations of emoji domain names.
Now, the ICANN Security and Stability Advisory Committee (SSAC) has published a report (pdf) warning against the use of these domain names.
The brief report notes that emoji in domain names are not allowed under the Internationalized Domain Names in Applications (IDNA) standard. They aren’t universally accepted and do not work across all devices.
They can also be difficult to decipher. Many emoji look similar to each other and some emoji can be “glued” together using a special zero width joiner (ZWJ) code point.
This creates a major problem:
The whole point of an identifier is to specify something unambiguously—this thing, as distinct from all other things. To a user, a single unmodified emoji might look exactly the same as its “glued together” counterpart, and systems that do not support emoji composition using a ZWJ will display the individual components of a “glued together” emoji as a sequence of separate emoji, with results that may visually be very different from what was intended. This is acceptable for interpersonal communication, particularly when it is augmented by shared context, but it is not acceptable for Internet identifiers, particularly DNS root labels that must be unambiguously resolved independent of any context.
Furthermore, Unicode 8.0 allows variants of emojis that change skin tone. This can make it even more confusing.
Another issue with emoji domain names is accessibility for visually impaired people.
The SSAC concludes its report with two recommendations:
1: Because the risks identified in this Advisory cannot be adequately mitigated without significant changes to Unicode or IDNA (or both), the SSAC recommends that the ICANN Board reject any TLD (root zone label) that includes emoji.
2: Because the risks identified in this Advisory cannot be adequately mitigated without significant changes to Unicode or IDNA (or both), the SSAC strongly discourages the registration of any domain name that includes emoji in any of its labels. The SSAC also advises registrants of domain names with emoji that such domains may not function consistently or may not be universally accessible as expected.