With a DBC you can re-issue it or more correctly ask for a reissue. So you have one or several for lots of safeocin. You want to pay somebody 4 safecoin. You take a DBS with >=4 safecoin and have it re-issued to the new id that’s gonna own it.
In fact here is a good read on more detail (just imagine each section is a bank) https://opaque.link/post/digitalmoneydbc/