Okay, I think I see the cause of the confusion. The tilde ~ does eliminate blank lines. However, setting $^A = "" does not reset the accumulator. You have to print it to do that.

Consider the following example based on your code snippet:

#Something tells me we're not programming in Perl anymore Toto. ;-)

for (1..2) {

    print "Run: ", $_, "\n";

    $^A = "";
    formline(<<'OUTPUT_TABLE', 1, 2);
@<<<<<<<      @<<<<<<<<<<<<
@<<<<<<<      @<<<<<<<<<<<<~
OUTPUT_TABLE

    $out .= $^A;
    print $out;
}

for (3..4) {

    print "Run: ", $_, "\n";

    $^A = "";
    formline(<<'OUTPUT_TABLE', 1, 2);
@<<<<<<<      @<<<<<<<<<<<<
@<<<<<<<      @<<<<<<<<<<<<~
OUTPUT_TABLE

    print $^A;
}
[download]

This gives the following output. Note the additional line in Run 2.

Run: 1
1             2
Run: 2
1             2
1             2
Run: 3
1             2
Run: 4
1             2
[download]

Therefore, you will have to re-organise your code to make sure that you print $^A.

--
John.