Why does a draft quote have no number?
Numbers are given at issue, so drafts you never issue leave no gaps. When you issue a quote, Deline says "A document number will be assigned and the original details and PDF preserved."
Can I choose my own quote prefix?
No. The Invoice number prefix in Settings → Business is for invoices only. Quote numbers always start with QT- or EST-.
What happens when the quote becomes an invoice?
The invoice draft gets the next invoice number only when you issue it, and it shows From quote … so the two stay linked.
Explanation written from the Deline app's own screens and texts (build eba146497 (Deline cf723fe1f)); it has no steps to check.