Yes, when you add multiple tasks to the invoice the whole group will get one Invoice number.
And yes, You can add there only tasks that were not invoiced yet.
Yes. All Projects (technically - Tasks) of a single Client, with a single currency, can be put on one invoice. It is up to you how you compose the invoices. You may do it per Project or Task, or by any batch you want.
Thank you Maciej, now I understand that a project can be considered like a task too. So, if I use the button "Add task-based Client invoices" of the invoincing section, I will could join several projects-tasks in just one document, XTRF will assign an invoice number for this group of tasks, rigth? This tool can be use it just with tasks that doesn't has an invoice created? rigth?
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