while(<DATA>){
if(/^(BCG-\d+)/){$bcg = $1} # current BCG, maybe?
if(/^( SNB\w+)/){$snb = $1} # current SNB, maybe?
@stuff = split(/\s+/); # put lines into an array
if ($stuff[3] eq 'BL-TRX'){ # if the BLT is found
  print "here's an interesting BCG:\n$bcg $snb @stuff\n";
  # report that it has been found
}
}


__DATA__
BCG-011  ULTRASITE     U  WO                                1 BC011 WO 
 05823 00051 BTS-025   U  WO                              0   0  
 SNBXCASD005X     RF                                                           3 
              TRX-001  U  WO      713  0  117 MBCCH         P 4 
              TRX-002  U  WO      729  0  117                 0 
 05823 00052 BTS-026   U  WO                               0   0 
 SNBXCASD005Y     RF                                                          3 
              TRX-005  U  WO      722  0  117 MBCCH         P 3 
              TRX-006  U  BL-TRX  731  0  117                 8 
 05823 00053 BTS-027   U  WO                                0   1