open OUT , '>', "outfilename" or die "unable to open out $!";

##</code><code>##

my $test = '10GBE_ADDR1';
#decide if first part of line has ABC901X_ ...
print "new record\n" if $test =~ m/^[A-Z0-9a-z]+_/;

##</code><code>##

sub print_record
{
   return unless @singlereference; #no work to do
   
   @singlereference = sort {$a <=> $b} @singlereference; 
   foreach my $col (@singlereference)
   {   
       print "$netname $col\n"; 
   }
   @singlereference =(); #reset array to empty
   return;
}