According to Nacha: “A POP entry is initiated by an Originator based on a written authorization and account information drawn from a check obtained from a consumer at the point of purchase. The check, which is voided by the merchant and returned to the consumer at the point of purchase, is used to capture the consumer’s routing number, account number, and check serial number, which are used to generate the ACH debit entry to the consumer’s account. POP entries are subject to special requirements under the Nacha Operating Rules. For example, authorizations for POP entries do not need to refer to an ability to revoke the entry, because revocation would not be practical for POP transactions where the customer obtains the goods or services and then leaves the point of purchase.[2]  In addition POP entries are subject to requirements as to the types of checks that can be converted to POP entries,[3]  the capture of MICR information,[4]  and receipts.[5]  The Nacha Operating Rules require that the POP entry contain specific information, including, but not limited to, the Receiver’s bank routing number, account number, serial number of the consumer’s source document, and location (city and state) of the electronic terminal used for the transaction.[6]”