Why are AP and/or Payroll checks designated as vouchers under Payment Type on my Check/Voucher register?

This happens when the vendor or employee has recently been setup to receive electronic payments and a pre-note was indicated.   

The pre-note designation will generate a check until the recipient’s bank account information in the ACH file is confirmed by the bank, this may take up to 4 check cycles. 

In the meantime, checks will be generated BUT due to the fact that the recipient has been confirmed as receiving electronic payments, the software reflects these checks as vouchers.