#!/usr/bin/perl -w
foreach  (
  '<xml version= "24.0" IP="1.1.2.3" baseVersion="beta_3" lastUpdate="22-Apr-06" >',
  '<xml IP="1.1.2.3" baseVersion="beta_3" version= "24.0" lastUpdate="22-Apr-06" >',
  q<<xml IP='1.1.2.3' baseVersion="beta_3" lastUpdate="22-Apr-06" version= '24.0'>>,
) {
    if(/<xml
      (?> \s+ [a-zA-Z][^\s\/=>'"]*  \s* = \s* (?: " [^"]* " | ' [^']* ' ) )*?
      \s+  version \s* = \s* (?:"([^"]*)"|'([^']*)') /x) {
        print "Match '$+' in $_\n";
    } else {
        print "No match in $_\n";
    }
}