Do you really need to store your conditions in a string? If the context permits it, you may as well store it in a code reference, as shown in the following session under the debugger:

  DB<1>  @field =  qw/0 0 0 0 0 0 PM 0 CAVENDI/;

  DB<2>  $code_ref = sub {$field[shift]  eq 'PM' && $field[shift] eq '
+CAVENDI'};

  DB<3>  $ignore_flag = $code_ref->(6, 8)

  DB<4> p  $ignore_flag
1
  DB<5>  $ignore_flag = $code_ref->(3, 8)

  DB<6> p  $ignore_flag

  DB<7> print "true" if $code_ref->(6, 8)
true
  DB<8>  print "true" if $code_ref->(3, 8)

  DB<9>
[download]

Here, I have added a feature (dynamic passing of the array subscripts as parameters to the coderef), but the subscripts might as well be hard coded as in your original example.