From the Swiss Implementation Guidelines QR-bill document, chapter 3.7 Notes about the QR-bill in PDF format:
If the QR-bill with payment part and receipt or the separate payment part with receipt are generated as a PDF document and sent electronically, the A6 format of the payment part and the receipt on the left must be indicated by lines. Each of these lines must bear the scissors symbol “
✂ ” or alternatively the instruction “Separate before paying in” above the line (outside the payment part).
Translation for the separation hint come from the Annex D: Multilingual glossary of the same document.