A|string|
B|string|
C|string|
D|string|

##</code><code>##

#!perl -w

my ($fs, $cs, $rs, $ec, $ss);
setdelimiters('|^~\&');


sub setdelimiters {
    ($fs, $cs, $rs, $ec, $ss) = map {quotemeta} split //, $_[0];
} 


use strict;


my $buffer="";
my $suppress = 0;
my $acct = "";

my @field;
my %newblock;
my %partofblock;


my @accounts = qw(77403 77404 77406 77407 77408 77409 77411 77412 77413 77414 77416 77418); 

 
my $infile  = 'c:/testfile.txt';
my $outfile = 'c:/idxfile.txt';
   
   
   open IN, "<$infile"  or die "Couldn't open $infile, $!";
   open OUT,">$outfile" or die "Couldn't open $outfile, $!";


$newblock{$_}    = 1 for qw(MSH);

$partofblock{$_} = 1 for qw(EVN PID FT1);


   while (<IN>) {


  if (/^(MSH)(.....)/) {
    setdelimiters($2);
  }

  @field = split /$fs/;


  if ($newblock{$field[0]}) {
    processbuffer();
  } elsif (!$partofblock{$field[0]}) {
    print STDERR "Possible error: segment=$field[0] line $.\n";
  }


  if ($field[0] eq "FT1") {

   
    foreach $acct (@accounts) {

      if ($field[8] = $acct ) {

            $suppress = 1;

      }
    }
  }
 
   $buffer .= "$_\n";      
}
processbuffer();


sub processbuffer {
  print OUT $buffer unless $suppress;
  $buffer="";
  $suppress = 0;
}