How to add a – on the registeration role

Good Morning everyone
I have installed The wordpress in my website and I found it a very good script..

when I try to apply the IDN Internationalized Domain Names on my blog registration it give me an error
The IDN required a character like this one
(-)
and the (-) is not valid on the blog registration
(Must be at least 4 characters, letters and numbers only.)
How can I apply or add a new role on my registeration
like register with a character –
I mean like this word
xn--mgbuhv1d8a
I want to signup in my blog with this word
xn--mgbuhv1d8a
and the error says
(Must be at least 4 characters, letters and numbers only.)
because —
How can I edit the role and make it OK to signup with (-)?
I hope that you understand what I want and give me the solution.
best wishs