Invoice Numbering

[Mark]

There are already several threads about this on the forum. Did you search for them as the Forum FAQ/Rules demand?

The developer, @lubos, stated the following:

Series of Number at printed documents

I’m not against this feature. If you want static prefix on all invoices, it will be possible. Footers will soon support ability to “inject” variables. Once that is done, I will implement ability to have custom document headers which will work similar to footers. That will conclude need for custom themes which are now obsolete due to being too complex for vast majority of users.