What can I do to accept both numbers & letters in that answer field?

I have a question about a form element.

 I added a question asking for a permit number on a form.  The permit number has letters and numbers in it, but the numbers form element only allows numbers to be entered.  

what can I do to accept both numbers & letters in that answer field?

Thanks,

Rob

This is a duplicate thread. I already posted a reply on your other thread. Here's the link: https://www.jotform.com/answers/1262367.

Thank you.