#!/usr/bin/perl
while(@data = <DATA>){
$au='';
$by='';
 for($i=0;$i<$#data;$i++){
if($data[$i]=~ m/^\.\.AU/){
                unless($data[$i+1]=~ /^\.\./){
                        $data[$i+1] =~ s/^\s+|\s+$//;
                        $au = $data[$i+1];
                }
        }
if($data[$i]=~ m/^\.\.BD/){
                unless($data[$i+1]=~ /^\.\./){
                        $data[$i+1] =~ s/^\s+|\s+$//;
                        $by = $data[$i+1];


                }
        }

}
print "$au,$by";
}

__DATA__
..HD:
..SE:
..AU:
C
..BD:
ON PAC
..BD:
BY PK
..SE:
..AU:
R CHRIS
..BD:
ON PAC-20 FOOTBALL
..BD:
ON PAC-30 BASKETBALL
..AU:
DK

[download]
How to make a pair of AU and BD and print all the values. If there are corresponding BD values how to concatenate with "," unless any other tag with matching with "..text:" is found. If no BD is found for the corresponding "AU",, we should not add comma. output should look like: 
C,ON PAC,BY PK
R CHRIS,ON PAC-20 FOOTBALL,ON PAC-30 BASKETBALL
DK

[download]

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