I don't have time to dive deep into your code right now, but, at least, change this:

      if ($start == 0)
         {
         goto NEXTLINE;
         }
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to a next statement with a label:

next NEXTLINE if $start == 0;
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See also Dijkstra's famous and classical article Go to statement considered harmful: https://files.ifi.uzh.ch/rerg/arvo/courses/kvse/uebungen/Dijkstra_Goto.pdf.