From this discussion, I started to have the idea that journal in an ERP is not really useful. This is a legacy from manual booking to organize physically the writings.
For now in Tryton, the journals are used for very few things:
provide the sequence for numbering the moves (as default value) which is fixed by XML to the same sequence for all standard journals.
provide a way to close partially a period per journal. This is a quite advanced feature for large setup with multiple accountant.
provide a report for cash journal. But Cash flow forecast is probably a better solution.
provide a criteria for analytic rules.
Of course, we have journal field scattered all over the accounting modules just to get a value when a procedure needs to create a move.
My proposal would be to move all the journal references to a specific module (e.g.
account_journal). This module will add the journal on the move and customize the filling of the number with criteria (like Allow diferent invoice sequences on the same period propose for invoice). It will also add journal for others modules.
Another advantage for this separation would be that we do no more need to create default journals by XML to get a working system out of the box. But this will be a manual operation if and only if this new module would be activated.