What are the middle digits of credit card number submissions indicated by "x"?

Collecting of credit card information is against JotForm Terms of use. That is why fields about credit card will be replaced with # hash symbols. 

If you want to have payment fields inside of your form you have to use one of JotForm payment tools. 

http://www.jotform.com/help/47-Order-Form-Basics 

http://apps.jotform.com/category/payment_processing 

http://www.jotform.com/help/165-Setting-Up-Your-First-Order-Form 

If you need any further assistance Feel free to contact us.

Thanks.