A small point of style, but

m{(?s)<div class="detailline_address">\s*(.*?)</div>}
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avoids endweight problems by pushing the modifier up front. There's also the case for always using (?msx) at the beginning of your regexes unless there's a damned good reason not to. In this case, the damned good reason not to is: "You're attempting to parse XML with a regular expression! Are you mad?"