All values should be undefined: $a = [+ $a || '' +]
$b = [+ $b || '' +]
$c = [+ $c || '' +]
$d = [+ $d || '' +]
$e = [+ $e || '' +]
First of all assign a value: [- $a = '(this is the value in $a)' -]
Now we have some 'Umlaute': [- $b = "$a äöü" -] Now lets look what we are getting from this:
[+ $a +] [+ $b +]
And now a and b together: [+ "$a$b" +]

Here we have some HTML tags within the perl code, Embperl will delete them!
[+ $c =
6 + 17 * 3 +] Embperl will also translate HMTL escapes to the right characters i.e. $a &lt; 6 will get the perl expression $a < 6:
[- $e = 2 -] [+ $d = $e < 6 +] Now they should have a value $a = [+ $a +]
$b = [+ $b +]
$c = [+ $c +]
$d = [+ $d +]
$e = [+ $e +]
[- $a = 1; $b = 0; $c = 5; $d = 'txt' -] [$if $a$] a
[$ endif$] [$if $a $] a
[$else$] not a
[$ endif $] [$ if $a$] a
[$if $b == 0$] b is null
[$else$] b is not null
[$endif$] [$ else$] not a
[$ endif $] [$ if $a$] a
[$if $b == 0$] b is null
[$else$] b is not null
[$endif$] [$ else$] not a
[$if $b == 0$] b is null
[$else$] b is not null
[$endif$] [$ endif $] [$ if !$a$] not a
[$if $b == 0$] b is null
[$else$] b is not null
[$endif$] [$ else$] a
[$if $b == 0$] b is null
[$else$] b is not null
[$endif$] [$ endif $] [- $i = 0 -] [$ while $i <= $#ffld $] [+ $ffld[$i] +] = [+ $fdat{$ffld[$i]} +] [- $j = 0 -] [$ while $j <= $i $] [+ $j++ +] [$ endwhile $]
[- $i++ -] [$ endwhile $]

[+ $c[$row][$col] +]

$tabmode = default

Display an two dimensional array with one, two and three columns !
Please take a look at the source in your browser to see the difference
[- undef @a ; undef @b ; $a[0][0] = 'a1/1' ; $a[1][0] = 'a2/1' ; $a[1][1] = 'a2/2' ; $a[2][0] = 'a3/1' ; $a[2][1] = 'a3/2' ; $a[2][2] = 'a3/3' ; $b[0][0] = 'b1/1' ; $b[1][0] = 'b2/1' ; $b[1][1] = 'b2/2' ; $b[2][0] = 'b3/1' ; $b[2][1] = 'b3/2' ; $b[2][2] = 'b3/3' ; $maxcol=99 ; -] $a[0][[0] = '1/1' ;
$a[1][[0] = '2/1' ;
$a[1][[1] = '2/2' ;
$a[2][[0] = '3/1' ;
$a[2][[1] = '3/2' ;
$a[2][[2] = '3/3' ;

$tabmode = default

[+ $a[$row][$col] +]

1	2	3
[+ $a[$row][$col] +]

[+ $b[2][$col] +]
[+ $a[$row][$col] +]

[+ $b[$row][$col] +] [+ $a[$row][$col] +]

[+ $HTML::Embperl::VERSION +]

[+ $tabmode +]

[+ local $tabmode = 1 +]

[- $i = 0 ; while ($i < 10) { $ii[$i++] = "ii[$i] = $i" ; } -] [- $i = 0 -] [$ while $i <= $#ffld $] [+ $ffld[$i] +] = [+ $fdat{$ffld[$i]} +] [- $j = 0 -] [$ while $j <= $i $] [+ $j++ +] [$ endwhile $]
[- $i++ -] [$ endwhile $] [- $i = 0 -] [$ while($i <= 2)$] [+ $i++ +] [$ endwhile $] [- %h = ('A' => 1, 'B' => 2, 'C' => 3) ; -] [- @a = ('a', 'b', 'c', 'd') ; -] [$ while ($v, $k) = each (%h) $] [+ "$v = $k" +]
[$ endwhile $] [- $i = 0 -] [$ while $i <= $#a $] [+ "\@a[$i] = $a[$i]" +]
[- $i++ -] [$ endwhile $] [- $i = 0 -] [$ do $] [+ "\@a[$i] = $a[$i]" +]
[- $i++ -] [$ until $i > $#a $] [$ foreach $v @a $] [+ $v +]
[$ endforeach $] [$ foreach $v (1, 3, 5, 7, 9) $] [+ $v +]
[$ endforeach $] [$ foreach $v (1..10) $] [+ $v +]
[$ endforeach $] [$ foreach $v(1..5) $] 2:[+ $v +]
[$ endforeach $] [- %hash = ( a=>1, b=>2, c=>3) -] [$ foreach $v(keys %hash) $] 3:[+ $v +]
[$ endforeach $] [- $i = 0 -] [$ do $] [+ "\@a[$i] = $a[$i]" +]
[$ while ($v, $k) = each (%h) $] [+ "$v = $k" +]
[$ foreach $fv (1, 3, 5, 7, 9) $] [+ $fv +]
[$ endforeach $] [$ foreach $fv () $] [+ $fv +]
[$ while ($wv, $wk) = each (%h) $] [+ "$wv = $wk" +]
[$ endwhile $] [$ endforeach $] [$ endwhile $] [- $i++ -] [$ until $i > $#a $] [- undef @a ; undef @b -] [$ if 1 $] x [$ foreach $a (@a) $] [$ foreach $b (@b) $] [$ endforeach $] [$ endforeach $] y [$ endif $]

[+ $ii[$row] +]