The IDN script does not contain other symbols apart from Cyrillic characters. Allowed UTF-8 characters from "а" (code 0430) to "я" (code 044F) and an auxiliary character "ё" (code 0451). The full list of UTF-8 symbols may be viewed on: http://www.unicode.org/charts/PDF/U0400.pdf
Supported IDN Scripts
The following IDN scripts are supported by .xn--p1acf.
Provide the LANGUAGE TAG corresponding to your desired IDN within the AddDomain command as X-IDN-LANGUAGE extension.
Get more information of "IDN tables", which represent permitted code points (letters) allowed for Internationalised Domain Name registrations in particular registries on IANA Repository of IDN Practices.