QR-Code = Quick Response Code   -  is a two-dimensional / 2D- / Matrix-Barcode

ISO/IEC 18004


List of QR Code format we found on some invoices
------------------------------------------------


* For SEPA QR payment Code format (Europe)
------------------------------------------
https://en.wikipedia.org/wiki/EPC_QR_code#Generators



* For ZATCA QR Code format (Saudi Arabia). Used when INVOICE_ADD_ZATCA_QR_CODE is set
-------------------------------------------------------------------------------------
https://www.pwc.com/m1/en/services/tax/me-tax-legal-news/2021/saudi-arabia-guide-to-develop-compliant-qr-code-for-simplified-einvoices.html

https://www.tecklenborgh.com/post/ksa-zatca-publishes-guide-on-how-to-develop-a-fatoora-compliant-qr-code

Method to encode/decode ZATCA string is available in test/phpunit/BarcodeTest.php 


* FOR QR-Bill in switzerland
----------------------------
Syntax of QR Code - See file ig-qr-bill-v2.2-fr.pdf  (more doc on https://www.swiss-qr-invoice.org/downloads/)
Syntax of complentary field named "structured information of invoice S1": https://www.swiss-qr-invoice.org/downloads/qr-bill-s1-syntax-fr.pdf
To test/validate: https://www.swiss-qr-invoice.org/validator/
