Is it possible to set id in Cyrillic?

Question

css

In fact, jsfiddle.net/0mc8badr/ works.
What could be the catch?

Answer 1

The value must be unique among all the IDs in the element's home subtree and must contain at least one character. The value must not contain any space characters.
There are no other restrictions on what form an ID can take; in particular, IDs can consist of just digits, start with a digit, start with an underscore, consist of just punctuation, etc.

www.w3.org/TR/html5/dom.html#the-id-attribute

Answer 2

ID and NAME tokens must begin with a letter ([A-Za-z]) and may be followed by any number of letters, digits ([0-9]), hyphens ("-"), underscores ("_") , colons (":"), and periods (".").
www.w3.org/TR/html401/types.html#type-name
There is a specification. What is written in it should be supported by all browsers, the rest they can support at will.

Answer 3

It is possible, but not necessary.