end_tag_handlers 
A hash { expression = \&handler}>. Sets element handlers that are called when the element is closed (at the end of the XML::Parser End handler). The handlers are called with 2 params: the twig and the tag of the element.

twig_handlers are called when an element is completely parsed, so why have this redundant option? There is only one use for end_tag_handlers: when using the twig_roots option, to trigger a handler for an element outside the roots. It is for example very useful to number titles in a document using nested sections:

  my @no= (0);
  my $no;
  my $t= XML::Twig->new( 
          start_tag_handlers => 
           { section => sub { $no[$#no]++; $no= join '.', @no; push @no, 0; } },
          twig_roots         => 
           { title   => sub { $_[1]->prefix( $no); $_[1]->print; } },
          end_tag_handlers   => { section => sub { pop @no;  } },
          twig_print_outside_roots => 1
                      );
   $t->parsefile( $file);
Using the end_tag_handlers argument without twig_roots will result in an error.