I usually use state and check for the end of line continuation character - something like this (pseudocode):

my $line='';
while (<INPUT>) {

  # build line
  chomp;
  if (/^(.*)\\$/) {    
     $line .= $1;  #or maybe $line .= "$1 "; ???
     next;
  }
  $line .= $_;

  # ... do line processing here ...
  if ($line =~ /^Data_Value/) { ... 
  } elsif ($line =~ /^Data_Group/) { ...
  } elsif ($line =~ /^Data_Raw/) { ...
  }

  # reset state
  $line = '';
}
[download]

The advantage of this approach is that it keeps the mechanics of reading in the data separate from the logic of processing the data. In the processing section you can get as fancy as you need without worrying about how it relates to the file's method of handling continuation lines.

Best, beth

This is a nice technique.

my $record_line=0;
my @records;
my $index=0;
while(<$DATA>){
   if ($record_line != 2){
      if(/^Data_Raw/){
         $records[$index]->{Data_Line}=$.;
         $record_line=2;
      }elsif(/^Data_group/){
         $record_line=1;
         my($title,@value)=split;
         $records[$index]->{Data_Group}=join(,' ',@value));
      }
   }elsif(/^Data_Value/){
      $index++;
      my($title,@value)=split;
      $records[$index]->{Data_value}=join(,' ',@value));
      $record_line=0;
   }
}
[download]

This seems very quick! I will work upon this to create my hash!
Since line continuation character is only in data_raw, and actual data is not important, just the line number is important, I do not need to bother with the "\" character!

Below I present some code which I have currently finalized.
The way of reading multiline record using prevline, and prevline2 is not really original, and I saw a colleague of mine doing this.

It looks very very simple and works, and I am currently writing the complete script with processing and all.

while (<INDATA>) {
        chomp;
        my $linenum = $.;

        if (/^data_raw/) {
            $indata{INFILE_RAW}{$linenum}{VALUE} = (split(/\s+/,$prevl
+ine))[-1];
            $indata{INFILE_RAW}{$linenum}{GROUP} = (split(/\s+/,$prevl
+ine2))[-1];    
        }
        $prevline2 = $prevline;
        $prevline = $_;
    }
[download]


The main reason I do like this, because I am inputting multiple files here. The governing key for all those files will be the line number. In the end the user will be presented statistics like this

Group name | Total Value
ABC             500
DEF             800
.
.
[download]


Now another file I will input will just contain the line numbers of invalid data items. So user will be shown another table which will be same as above, but with invalids removed. Another table like the above will be shown which will be for the "invalids" file. In all this, the key is the line number which identifies what to subtract, the line number of the data_raw to be precise.

use warnings;
use strict;
use Data::Dumper;

my (%result, $subhash);

while (<DATA>) {
    if (/^Data_Value/ ... /^Data_raw/) {
        my @value = split;
        my $value = $value[0] = '';
        $value = "@value";


        if (/^Data_Value/) {
            $subhash = $value;
            $result{$subhash} = {};
        }

        $result{$subhash}->{Data_Group} = $value if /^Data_Group/;
        $result{$subhash}->{Data_raw} = $. if /^Data_raw/;
    }
}

print Dumper \%result;

__DATA__
Data_Value -999
Data_Group Clock453
Data_raw -from point_q/point2 \
         -of point_a/abc/Q/D \
         .
         .
         -to endpoint/abc/CK
Data_Value -123
Data_Group Clock453
Data_raw -from point_q/point2 \
         -of point_a/abc/Q/D \
         .
         .
         -to endpoint/abc/CK
Data_Value -666
Data_Group Clock453
Data_raw -from point_q/point2 \
         -of point_a/abc/Q/D \
         .
         .
         -to endpoint/abc/CK
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user@unforgiven:~$ perl tst.pl
$VAR1 = {
          ' -123' => {
                       'Data_Group' => ' Clock453',
                       'Data_raw' => '10'
                     },
          ' -999' => {
                       'Data_Group' => ' Clock453',
                       'Data_raw' => '3'
                     },
          ' -666' => {
                       'Data_Group' => ' Clock453',
                       'Data_raw' => '17'
                     }
        };
[download]

Hmm the use of ellipses (...)
This seems to be quite interesting. I have never used this to parse through multiple records

With perl I learn everything new each day, and to consider that I have been programming for past 2 years! </p Thanks

These are questions you should ask yourself before starting to prematurely optimise your program.