In my company we decided to use Odoo ERP to create our sales invoices, but the problem is that the external API uses XML-RPC, currently I work with Codeigniter (php) and I have managed to connect and create contacts, but I can not find documentation about what parameters to send, what I am doing at this moment is to look for some invoice that I have created in the platform and then the parameters that I send, but I find this a slow process and I do not understand some things like searching. The documentation of them is limited. Does anyone have any experience in this or do they have a website with a tutorial or what parameters should I send? Thank you.