It's not a special variable. It's just a name I made up to control the level of auditing.

So, no, there's nothing magical about it at all. You need to write the code which handles it yourself. I hoped that I had made that obvious with the sample code:

print LOG 'Starting processing at ', scalar localtime, "\n"
  if $audit_level > 0;
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I apologise for any confusion caused :-)