Here is one possible solution.

#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my $currec = undef;
my @recs =();

while (<DATA>)
{
    if ( /^Record\s+(\d+)/)
    {
        $currec = $1
    }
    elsif ( /^
            (\S+)   # non spaces. This is the key name
            \s+     # some spaces follows
            :       # and a colon
            \s+     # more spaces
            [^\[]+  # any non bracket character
            \[      # an opening bracket
            (
            [^\]]*  # any more characters before a closing bracket
            )
            \]      # a closing bracket
            /x)
    {
        $recs[$currec]{$1} = $2;
    }
}

print Data::Dumper->Dump([ \@recs ], ['original']);

my @twelves = grep { $recs[$_]->{Ref} == 12 } 0.. $#recs;

print Data::Dumper->Dump( [ \@{[ @recs[@twelves] ]} ], ['twelves']);

__DATA__
=================================================
Record 0

Name                  : John [John]
I/C                   : >123< [123]
Sex                   : 'Male' [Male]
Ref                   : >12< [12]
==================================================
Record 1

Name                  : Pretty [Pretty]
I/C                   : >125< [125]
Location              : 'Female' [Female]
Ref                   : >12< [12]
==================================================
Record 2

Name                  : Kim [Kim]
I/C                   : >124< [124]
Location              : 'Male' [Male]
Ref                   : >11< [11]
==================================================
[download]

And the output:

$original = [
              {
                'I/C' => '123',
                'Ref' => '12',
                'Sex' => 'Male',
                'Name' => 'John'
              },
              {
                'I/C' => '125',
                'Ref' => '12',
                'Location' => 'Female',
                'Name' => 'Pretty'
              },
              {
                'I/C' => '124',
                'Ref' => '11',
                'Location' => 'Male',
                'Name' => 'Kim'
              }
            ];
$twelves = [
             {
               'I/C' => '123',
               'Ref' => 12,
               'Sex' => 'Male',
               'Name' => 'John'
             },
             {
               'I/C' => '125',
               'Ref' => 12,
               'Location' => 'Female',
               'Name' => 'Pretty'
             }
           ];
[download]

This should be more than enough for a start.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.