Dolibarr ERP CRM is a modern software package to manage your company or foundation's activity (contacts, suppliers, invoices, orders, stocks, agenda, accounting, ...). it's an open source Web application (written in PHP) designed for businesses of any sizes, foundations and freelancers.
In the interests of helping others not lose so much time looking for information, it seems that the only explanation of these unique tax parameters and how to use them is here: https://www.dolibarr.es/index.php/erp-dolibarr/ultimas-noticias-dolibarr/166-nuevo-manejo-del-irpf-para-profesionales Please advise if this is documented elsewhere. If not, I'll put it in the Wiki.