According to the AFIP specification, invoices may have a QR code with the transaction data. The specification can be viewed at https://www.afip.gob.ar/fe/qr/conceptos-generales.asp
Athento includes an operation called op_extract_qr_invoice_argentina. This operation obtains the QR code data as a feature.
Subsequently, these characteristics can be consulted later with the expression fil.gfv('CHARACTERISTICS'). For example, to query the CUIT, it would be fil.gfv('afip.factura.cuit')