Can the QR-bill be used for paper-based payment instructions?

What is an "Alternative procedure"?

Do I have to fill in the field "Alternative procedure" when I issue an invoice?

How can the QR-bill be used for online services?

Can the QR-bill be used for cash payments at the Swiss Post branch, at a branch with partner or at the bank counter?

Can the invoice recipient also pay a PDF invoice at the post office counter or send the printed payment order on paper to his bank?

Is there any need for action when using account payable systems?