while (<>) {
    # replace italics and bold
    s{^([ib])\s+(.*)}[<$1>$2</$1>];

    # find ordered lists
    if (my $hit= /^\[\s*$/ .. /^\]\s*$/) {
      if ($hit==1)      { print "<ol>\n";  next; }
      if ($hit=~ /e0/i) { print "</ol>\n"; next; }
      s[^][<li>];
      s[$][</li>];
    }
  }