>perl -wMstrict -le
"my $s =
   '<a>foo</a><bc>bar</bc> <def>baz</def> \"x\" <ghij>%&*</ghij>';
 print qq{'$s'};
 ;;
 $s =~ s{ < ([^>]+) > ((?: (?! </ \1) .)*) </ \1 > }{$2}xmsg;
 print qq{'$s'};
 ;;
 ;;
 $s = '<B>foo</ b > <efg>bar</efg> \"stuff\" <cD >*&!</ Cd>';
 print qq{'$s'};
 ;;
 my @tags = qw(b cd);
 my $tag  = join '|', @tags;
    $tag  = qr{ (?i) $tag }xms;
 use re 'eval';
 $s =~ s{ < \s* ($tag) \s*  >
          ((?: (?! </ \s* \1) .)*)
          </ \s* ([^>]*) (?(?{ lc($1) ne lc($^N) }) (*F)) \s* >
        }
        {$2}xmsg;
 print qq{'$s'};
"
'<a>foo</a><bc>bar</bc> <def>baz</def> "x" <ghij>%&*</ghij>'
'foobar baz "x" %&*'
'<B>foo</ b > <efg>bar</efg> "stuff" <cD >*&!</ Cd>'
'foo <efg>bar</efg> "stuff" *&!'

##</code><code>##

>perl -wMstrict -le
"my $s =
   '<B>foo</ b > <EfG>bar</eFg> \"stuff\" <cD >*&!</ Cd> <x>baz</x>';
 print qq{'$s'};
 ;;
 my $ar_tag_delete_content = [ 1, tag_group_regex(qw(efg) ) ];
 my $ar_tag_leave_content  = [ 0, tag_group_regex(qw(b cd)) ];
 ;;
 for my $pass ($ar_tag_leave_content, $ar_tag_delete_content) {
   my ($delete_content, $tag) = @$pass;
   use re 'eval';
   $s =~ s{ < \s* ($tag) \s*  >
            ((?: (?! </ \s* \1) .)*)
            </ \s* ([^>]*) (?(?{ lc($1) ne lc($^N) }) (*F)) \s* >
          }
          { $delete_content ? '' : $2 }xmsge;
   print qq{'$s'};
   }
 ;;
 sub tag_group_regex {
   my $alternation = join '|', @_;
   return qr{ (?i) $alternation }xms;
   }
"
'<B>foo</ b > <EfG>bar</eFg> "stuff" <cD >*&!</ Cd> <x>baz</x>'
'foo <EfG>bar</eFg> "stuff" *&! <x>baz</x>'
'foo  "stuff" *&! <x>baz</x>'

##</code><code>##

>perl -wMstrict -le
"my @strings = (
   '<B>foo</ b > <EfG>bar</eFg> \"stuff\" <cD >*&!</ Cd> <x>baz</x>',
   '<b>fee</B> P <b>fie</B> Q <efg>foe</EFG> R <efg>fum</EFG> S',
   '<b>hee</b> W <b>hie</b> X <efg>hoe</efg> Y <efg>hum</efg> Z',
   );
 ;;
 my $ar_keep_tag_content = [ 1, tag_group_regex(qw(b cd)) ];
 my $ar_kill_tag_content = [ 0, tag_group_regex(qw(efg) ) ];
 ;;
 for my $s (@strings) {
   print qq{'$s'};
   for my $pass ($ar_keep_tag_content, $ar_kill_tag_content) {
     my ($keep_content, $tag) = @$pass;
     $s =~ s{ < \s* ($tag) \s* >  (.*?)  </ \s* (?i) \1 \s* > }
            { $keep_content ? $2 : '' }xmsge;
     print qq{'$s'};
     }
     print '';
   }
 ;;
 sub tag_group_regex {
   my $alternation = join '|', @_;
   return qr{ (?i) $alternation }xms;
   }
"
'<B>foo</ b > <EfG>bar</eFg> "stuff" <cD >*&!</ Cd> <x>baz</x>'
'foo <EfG>bar</eFg> "stuff" *&! <x>baz</x>'
'foo  "stuff" *&! <x>baz</x>'

'<b>fee</B> P <b>fie</B> Q <efg>foe</EFG> R <efg>fum</EFG> S'
'fee P fie Q <efg>foe</EFG> R <efg>fum</EFG> S'
'fee P fie Q  R  S'

'<b>hee</b> W <b>hie</b> X <efg>hoe</efg> Y <efg>hum</efg> Z'
'hee W hie X <efg>hoe</efg> Y <efg>hum</efg> Z'
'hee W hie X  Y  Z'