G'day hotpelmen,

The oldest version I have is v5.30.0, so I couldn't attempt to replicate your results. I had a look in perlform for a number of versions but couldn't find any change. My look was brief; you may want to study more closely:

• https://perldoc.perl.org/5.16.0/perlform
• https://perldoc.perl.org/5.32.0/perlform
• https://perldoc.perl.org/5.36.1/perlform

I suspect you may be right about '~' & '~~'. There does seem to be some conflict between "perlform: Suppressing Lines Where All Fields Are Void" and "perlform: Repeating Format Lines".

"Assuming I still want to use format, how would you advise to overcome this and achieve printing of whitespace values into separate lines of report?"

This code, pm_11152452_testformat.pl, worked for me.

#!/usr/bin/env perl

use strict;
use warnings;
use autodie;
use constant REP_LINE_MAX_LENGTH => 3;

# For demo only
print "Perl version: $^V\n";

my $outfile = '/tmp/pm_11152452_test.txt';

my ($date, $reference, $rep_line);

format REP_TOP =
@<<<<<<<<<<<<<<< @>>>>>>>>>>>>>>
$date, $reference
.

format REP =
^*~~
$rep_line
.

$date = '11/11/2011';
$reference = 'REF123';

open my $fh, '>', $outfile;

$fh->format_name('REP');
$fh->format_top_name('REP_TOP');
$fh->autoflush(1);
$fh->format_lines_per_page(10);

for (@ARGV) {
    $rep_line = substr($_, 0, REP_LINE_MAX_LENGTH);
    write $fh;
}

# For demo only
system cat => $outfile;
unlink $outfile;
[download]

I kept REP_LINE_MAX_LENGTH very short for demo purposes; you'll want it to be 33 (if I counted correctly). I tested it on three versions:

$ ./pm_11152452_testformat.pl zero one " " two three " " four five
Perl version: v5.30.0
11/11/2011                REF123
zer
one

two
thr

fou
fiv

$ ./pm_11152452_testformat.pl zero one " " two three " " four five
Perl version: v5.32.0
11/11/2011                REF123
zer
one

two
thr

fou
fiv

$ ./pm_11152452_testformat.pl zero one " " two three " " four five
Perl version: v5.36.0
11/11/2011                REF123
zer
one

two
thr

fou
fiv
[download]

See how you go with 5.16.