now $x consists of a single byte.

Yes, that's what I call a byte. So maybe it's my definition, not my term that's unclear.

which is defined in terms of substr, for which the UTF8 flag *does* matter

Ah, there's the problem. "The UTF8 flag doesn't matter" means different things to us. For a given string, substr will always return the same value regardless of the UTF8 flag, so I say the UTF8 doesn't matter to substr. 

my $flag_is_0 = "\xC9ric";  utf8::downgrade($flag_is_0);
my $flag_is_1 = "\xC9ric";  utf8::upgrade($flag_is_1);

say substr($flag_is_0, 0, 1) eq substr($flag_is_1, 0, 1) ?1:0;  # 1

[download]

I shall endeavor to find something clearer.

just do mind that not all people share your definition

Thus this post. If I refer them to this post, they can understand what I say even if their definitions are different.

In reply to Re^2: Jargon relating to Perl strings by ikegami
in thread Jargon relating to Perl strings by ikegami

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