“There is no such thing as a Unicode file.”

A sample: (Note well the source!)

FAQ - UTF-8, UTF-16, UTF-32 & BOM

unicode.org/faq/utf_bom.html - Cached

In that form, the BOM serves to indicate both that it is a Unicode file, and which of the formats it is in. Examples: ...

See, even they recognise the need. Their mistake was not making it compulsory!

What do you not understand about constructional English?

1.    A text file: a file that contains text.
2. An image file: a file that contains an image.
3.    A video file: a file that contains video.
4. A unicode file: a file that contains unicode.

Now, stop being such an ass. As diversionary tactics go, it's a lousy one.

You've still failed to answer the question. I posed way back there:

Explain how you are going to solve the problem of sorting names written in [a combination of] Latin, Cyrillic, Arabic, Farsi, Thai, Chinese, Japanese, Urdo, Gaelic Ge'ez, Osmanya, Tifinagh ... et al.