Are you talking about the 'Check Printed' field? If that's it, that's what the help says about this field
Check Printed Field
The Gen. Journal Line Table
This field shows whether a check has been printed for the amount on the payment journal line. A check mark indicates that a check has been printed.
The field is used if you chose Computer Check in the Bank Payment Type field on the payment journal line and indicates whether you can post the journal line. If the payment type is Computer check, you must print the check before you can post the payment journal line.
To print a check, click the Payment button and then choose Print Check.
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Check Printed Field
The Gen. Journal Line Table
This field shows whether a check has been printed for the amount on the payment journal line. A check mark indicates that a check has been printed.
The field is used if you chose Computer Check in the Bank Payment Type field on the payment journal line and indicates whether you can post the journal line. If the payment type is Computer check, you must print the check before you can post the payment journal line.
To print a check, click the Payment button and then choose Print Check.