An easier solution – let us create a prefix for any numbering for different situations. Per-template is one option, but I'm more interested in per-client numbering (ie "CLIENT-001") or per-repeating invoice ie ("MONTHLY-001"), with a general catch-all (ie "INVOICE-001") for anything that doesn't have a prefix. All Xero needs to do is let us assign a custom prefix in these situations, and then do a quick lookup to increment the next sequential number for the prefix when the invoice gets created.
An easier solution – let us create a prefix for any numbering for different situations. Per-template is one option, but I'm more interested in per-client numbering (ie "CLIENT-001") or per-repeating invoice ie ("MONTHLY-001"), with a general catch-all (ie "INVOICE-001") for anything that doesn't have a prefix. All Xero needs to do is let us assign a custom prefix in these situations, and then do a quick lookup to increment the next sequential number for the prefix when the invoice gets created.