<?php
$acronym = "ASCII" ;
$fulltext = "American Standard Code for Information Interchange" ;
$re = "/(?s)<pre[^<]*>.*?<\\ /pre>(*SKIP)(*F)|\\ b$acronym \\ b/" ;
$str = "<pre>ASCII\n Sometext\n Moretext</pre>More text \n ASCII\n More text<pre>More\n lines\n ASCII\n lines</pre>" ;
$subst = "<acronym title=\" $fulltext \" >$acronym </acronym>" ;
echo $result ;
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