If you want to avoid printing undef's and pure whitespace: 
print $op if defined($op) and $op =~ /\S/;

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If any spaces at all are verboten, you want 
print $op if defined($op) and $op !~ /\s/;

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It would help if you clearly stated what you did and did not want to print.

In reply to Re: printing the subscript separator by trammell
in thread printing the subscript separator by jacques

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