Hi again,
This is not a perfect way to achieve it but I used this script customisation in order to have something like YYYYMMDD-###### working for all tickets. Problem is that there is no automatic back to 0 ticket number per day or mounth or year. If you want to get back to 0 , you have to do it manually every time.
For now that's enough for me but I would really appreciate a real-date included sequence...
!!!! Seems to be incompatible with 1.14 stable !!!! I will post later otherwise...
Maybe for a late version of OSticket...