But this sections need to be exactly as they where declared, soo, if some variable exists there can't be parsed.

Soo, this data:

$data = <<DATAFOO;
bla bla bla $globalvar
DATAFOO

print "$data\n" ;
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bla bla bla
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bla bla bla $globalvar
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Looking at perldoc I found

## From perldiag:
=item Use of bare << to mean <<"" is deprecated

(D deprecated) You are now encouraged to use the explicitly
quoted form if you wish to use an empty line as the 
terminator of the here-document. 

## From perlop

    Customary  Generic        Meaning         Interpolates
    ''     q{}          Literal          no
    ""    qq{}          Literal          yes
    ``    qx{}          Command          yes*
        qw{}         Word list          no
    //     m{}       Pattern match      yes*
        qr{}          Pattern          yes*
         s{}{}        Substitution      yes*
        tr{}{}      Transliteration      no (but see below)
        <<EOF                 here-doc            yes*

    * unless the delimiter is ''.
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Soo, testing some codes I saw that is possible to write that:

$data = <<'DATAFOO';
bla bla bla $globalvar
DATAFOO

print "$data\n" ;
[download]

bla bla bla $globalvar
[download]

OK, I found what I want. But the use of <<'DELIMITER'; is right/maintained? It works, but I never saw that and is not well documented, or I'm the only one that doesn't know that?