Yes $_table{'Ö'} is an example. There is no use utf8;. No identifiers neither Unicode strings are builtin into the module. The hash is sourced via this function: 
my %_table = ();

    sub load_map
    {
      open( UTF8, "<:encoding(utf8)", 'tab.bin' ) || die "can't open t
+ab.bin : $!";

      while( <UTF8> ) {
        chomp;
        my $offset = index($_,' ');
        my $bin    = substr($_,$offset+1);
        my $esc    = substr($_,0,$offset);
        $_table{$bin} = $esc;
      }
      close( UTF8 );
    }

[download]
A Dump of a (short) received string is this: 
SV = PVMG(0x12fca50) at 0x134f698
  REFCNT = 4
  FLAGS = (PADMY,POK,pPOK,UTF8)
  IV = 0
  NV = 0
  PV = 0x1361200 "                           <entry>R\303\226CHLING EN
+GINEERING PLASTICS (UK) LIMITED</entry>"\0 [UTF8 "                   
+        <entry>R\x{d6}CHLING ENGINEERING PLASTICS (UK) LIMITED</entry
+>"]
  CUR = 85
  LEN = 88

[download]
Going to think about that SSCCE. Thanks

UPDATE: here the SSCCE: 

use strict;
use utf8;     # used only for this SSCCE to set scalar $SGML at line 4
+4
use Devel::Peek qw (Dump);
use Encode qw(encode_utf8);

binmode(STDOUT, ":utf8");

my %_table = ();
# -----------------------------------
sub load_map
{
   while( <DATA> ) {
     chomp;
     my $offset = index($_,' ');
     my $bin    = substr($_,$offset+1);
     my $esc    = substr($_,0,$offset);
     $_table{$bin} = $esc;
   }
}

# -----------------------------------
sub _mapchar
{
   my ($char) = @_;
   if ( $char !~ /[\r\n\s]/) {
        my $nbytes = length encode_utf8($char);
        if ($nbytes > 1) {
        $char = exists $_table{$char} ? $_table{$char} : '?';
        }
   }
   return $char;
}
# -----------------------------------
sub escapeUTF8
{
   my ( $sgml_r) = @_;

   Dump $$sgml_r;
   $$sgml_r =~ s/(.)/_mapchar($1)/eg;
}

load_map();

my $SGML='RÖCHLING';
print "1: $SGML\n";
escapeUTF8(\$SGML);
print "2: $SGML\n";

__DATA__
&dollar; $
&Ouml; Ö
&raquo; »
~

[download]

it works, but still the regex is on every char

In reply to Re^2: Substitute some Unicodes with their escapes by jjmoka
in thread Substitute some Unicodes with their escapes by jjmoka

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