use FileHandle;

format foo_rec =
FOO      @>>>>>>>
         $flds[3]
.

format dflt_rec =
@<<<<<<< @>>>>>>>  @>>>>> @>>>>>
$flds[2] $flds[3]  $flds[5] $flds[9]
.

while (<FH>) {
   my @flds = split /\|/, $_;
   if ($flds[0] eq 'foo') {
      format_name FS "foo_rec";
      write FS;
   }
   else {
      format_name FS "dflt_rec";
      write FS;
   }
}