The output of the script is in the original post: 
Ein <#c3><#96>konomisches Modell
Ein <#d6>konomisches Modell 1
Ein <#d6>konomisches Modell 1

[download]
I expected to see <#c3><#96> in all three cases. The actual confusion on the test script turns out to be a bug in the "print_chrcodes" function. I either should have used Devel::Peek, or ensured the function used "use bytes": 
sub print_chrcodes
{
    my $str = shift;
    my $ret;
    use bytes;  #<<<<<<<<<here
    foreach my $ascval (unpack("C*", $str)) {
        if($ascval == 13) {
            $ret .= '<cr>';
            next;
        }
        if($ascval == 10) {
            $ret .= '<nl>';
            next;
        }
        if($ascval <  128) {
            $ret .= chr($ascval);
            next;
        }
        $ret .= sprintf ("<#%x>",$ascval) if($ascval >= 128);
    }
    return $ret;
}

[download]
What I was diagnosing was a situation where Unicode did not cleanly go through Storable::nfreeze, a database, then Storable::thaw : 
$hash->{TITLE}="f\xc3\xa4ce=\xe2\x98\xbb";
print "TITLE=$hash->{TITLE}\n";
my $nfreeze = Storable::nfreeze($hash);
my $obj     = Storable::thaw($nfreeze);
print '${^UNICODE}='.${^UNICODE}."\n";
print "TITLE=$obj->{TITLE}\n";

[download]
That eventually resolved itself. The setting of PERL_UNICODE=SAD vs. PERL_UNICODE=0 was masking the true problem, as it allowed certain sequences perl thought of as latin1 to be seen on the terminal as their equivalent utf-8 character (in my test case, black smiling face ☻).

So in the end with: use encoding "utf-8-strict"; added to the script, and PERL_UNICODE=SAD, and proper terminal settings, and Apache Accept-Charset, and SET CLIENT-ENCODING UTF8 I'm round tripping Uncode through the entire Browser->Apache->Perl->Database->Perl->Apache->Browser System.

Thanks for the help.

In reply to Re^2: Why does perl's internal utf8 seem to allow single-byte latin1? by brycen
in thread Why does perl's internal utf8 seem to allow single-byte latin1? by brycen

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