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 +]

Ok.

[# This is an Embperl comment it will totaly removed from the html source #] [# [+ "blabla" +] it will also hide perl code #]