undef $/;
%oli = ("NLI" => "OL TYPE\"1\"", "ALI" => "OL TYPE\"A\"", "aLI" => "OL TYPE\"a\"", "RLI" => "OL TYPE\"I\"", "rLI" => "OL TYPE\"i\"");

open (FIN, "< C:\in.txt") || die "can't open";
$content = <FIN>;
$content =~s /(<NLI>.*?\n)(?!<(?:[0-9]?NLI|[0-9](?:B|A|a|R|r)LI)>)/<OL TYPE="1">\n$1<\/OL>\n/gs;
$content =~s /(<BLI>.*?\n)(?!<(?:[0-9]?BLI|[0-9](?:N|A|a|R|r)LI)>)/<UL TYPE="DISC">\n$1<\/UL>\n/gs;
$content =~s /(<ALI>.*?\n)(?!<(?:[0-9]?ALI|[0-9](?:B|N|a|R|r)LI)>)/<OL TYPE="A">\n$1<\/OL>\n/gs;
$content =~s /(<aLI>.*?\n)(?!<(?:[0-9]?aLI|[0-9](?:B|N|A|R|r)LI)>)/<OL TYPE="a">\n$1<\/OL>\n/gs;
$content =~s /(<RLI>.*?\n)(?!<(?:[0-9]?RLI|[0-9](?:B|N|A|a|r)LI)>)/<OL TYPE="I">\n$1<\/OL>\n/gs;
$content =~s /(<rLI>.*?\n)(?!<(?:[0-9]?rLI|[0-9](?:B|N|A|a|R)LI)>)/<OL TYPE="i">\n$1<\/OL>\n/gs;

$content =~s /(<(OL|UL)[^>]*>)((?:(?!<\/\2>)|.)*?)(<\/\2>)/$1.&rep($3.$4)/gse;

sub rep{
my ($line) = @_;
$line =~s /<(\/?)(?:N|B|A|a|R|r)LI>(?!\n<[0-9])/<$1LI>/gs;
$line =~s /<\/((?:N|A|a|R|r)LI)>(.*?\n)(?=(?:<LI>|<\/OL>))/\n<$oli{$1}>$2<\/OL><\/LI>\n/gs;
$line =~s /<\/BLI>(.*?\n)(?=(?:<LI>|<\/OL>))/\n<UL TYPE="DISC">$1<\/OL><\/LI>\n/gs;
$line =~s /(<(OL|UL)[^>]*>)((?:(?!<\/\2>)|.)*?)(<\/\2>)/$1.&rep1($3.$4)/gse;
return "$line";
}

sub rep1{
my ($line) = @_;
$line =~s /<(\/?)1(?:N|B|A|a|R|r)LI>(?!\n<2)/<$1LI>/gs;
$line =~s /<\/1((?:N|A|a|R|r)LI)>(.*?\n)(?=(?:<LI>|<\/OL>))/\n<$oli{$1}>$2<\/OL><\/LI>\n/gs;
$line =~s /<\/1BLI>(.*?\n)(?=(?:<LI>|<\/OL>))/\n<UL TYPE="DISC">$1<\/OL><\/LI>\n/gs;
$line =~s /<(\/?)2(?:N|B|A|a|R|r)LI>/<$1LI>/gs;
return "$line";
}

open (FOUT, "> C:\out.txt") || die "can't open";
print FOUT $content;