No problem. This just requires that the <no>...</no> tags are put in an array. But we use $numbers[-1] instead of $numbers[$#numbers].

#! /usr/bin/perl -w
use strict;

my $text;
if (open INPUT, '<data')
{
  local $/;
  $text = <INPUT>;
  close INPUT;
}

while ($text =~ /<\?split \?>(.*?)(?=<\?split \?>)/sg)
{
  my $fragment = $1;
  my ($h1)    = $fragment =~ /<h1>(.*?)<\/h1>/is;
  my @numbers = $fragment =~ /<no>(.*?)<\/no>/isg;

  if (open OUTPUT, ">${h1}-nr${numbers[0]}to${numbers[0-1}.xml")
  {
    print OUTPUT $fragment;
    close OUTPUT;
  }
}

exit 0;
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