while (my $line=<PF>) {
    chomp($line);
    my @arrAbs=split (/\|/,$line);
    my $ID=$arrAbs[0];
    my $Title=$arrAbs[1];
    my $Abs=$arrAbs[2];
    @arrAbs=split (/\./,$Abs);
    print OF"$ID|";

    for (my $SentenceNumber=0;$SentenceNumber<=$#arrAbs ;$SentenceNumber++) {
        my $i=$SentenceNumber+1;
        print OF "<".$i.">";
        my $Sentence=$arrAbs[$SentenceNumber];
        my @arrAbsSen=split (' ',$Sentence);

        foreach my $word(@arrAbsSen) {

#to match terms in the list, stored in %{$List1Ref}.
            if (exists(${%{$List1Ref}}{uc($word)})) { 
                print OF "$word ";
            }
            
            else {
                foreach my $p (sort keys (%{$List1Ref})) {
                    if (exists(${%{${%{$List1Ref}}{$p}}}{uc($word)})) { 
                        print OF "mainterm:$p:matchedterm:$word ";
                        last; 
                    }
                }
            }
        }
    @arrAbsSen=();
    }
    print OF "\n";
    @arrAbs=();
}