Hello Everybody,
I want to give my invoices a number like : (actual month -1)/invoice Serial number, for example, this is month 9, I want that the system gives my invoices a number like 08/39000, I can now only give my invoices a number like : 09/39000
I tried in the prefix to do : %((month)s-1) but the minus 1 does'nt work.
Thanks in advance for your precious help.