But I don't know what's the function of "$dat=~s/"\//"http:\/\/dis.embl.de\//g;"

It substitutes "/ with "http://dis.embl.de/, which presumably has the effect that IE will fetch URIs affected by the substitution remotely instead of trying to load them from your local disk (where tmp2.html resides).

For example:

my $dat = '<img src="/foo.jpg">';

$dat=~s/"\//"http:\/\/dis.embl.de\//g;

print $dat;   # <img src="http://dis.embl.de/foo.jpg">
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