in reply to Re^2: using binmode() to override default encoding specified in "use open"
in thread using binmode() to override default encoding specified in "use open"

That is incorrect. "utf8" is an extension to UTF-8 used by Perl internally. "UTF-8" is the standard encoding. (The names are case-insensitive.)

I have no idea why that pages says they are equivalent. They are not. See :encoding(UTF-8) vs :encoding(utf8) vs :utf8.

In Section Seekers of Perl Wisdom