encoding - ASCII / UTF8 set random? -

i have tried program called utfcast professional. checkes file encoding.

when write code use sublime text.

random encoding

what files utf8 , files ascii/utf8. appears set random. of them set "bom: no".

• why files utf8 , ascii/utf8?
• is possible in cases not know if it's ascii or utf8?
• should worried future encoding problems? have not have far.

(i prefer utf8)

a plain text file not in way save encoding it's in anywhere. program purportedly tells encoding file in definition giving best guess based on content of file. now, since file contains characters present in ascii , saved utf-8 indistinguishable pure ascii file, either answer valid. latin-1 , large number of other answers valid.

so answer why program randomly outputs 1 or other because detection algorithm triggers 1 or other based on characteristics of file content. program author can tell why. file encoded utf-8 without bom. whatever application tells thinks is entirely application.