This is untested but should work, especially if each AAA code is seperated by a comma. 
my @list;
while (<INFILE>){
   my @line = split/,/,$_;
   for (@line){
      m/(AAA.\d)/;
      push @list, $1;
   }
}

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In reply to Re: accumulating rex-exp matches in an array by Anonymous Monk
in thread accumulating rex-exp matches in an array by waxmop

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