A: A_value
B: B_value
C: C_value

A: A_value
B: B_value
C: C_value

##</code><code>##

my @data = readOnly( "Data.txt" );
my $i = 0; my $index = 0;
my $a; my $b; my $c;

while( $i < @data )
{
    if( $data[$i] =~ /A:/ )
    {
        ( , $a) = split( /: /, $data[$i++] );
        ( , $b) = split( /: /, $data[$i++] );
        ( , $c) = split( /: /, $data[$i++] );

        if( exists $baseline{$a} )
        {
            $hash[$index++] = {
                                a => $a,
                                b => $b,
                                c => $c,
                              };
        }
    }
}