I have a question regarding creating qweb reports. I went through the link (https://www.odoo.com/documentation/8.0/reference/reports.html) dealing with qweb reports and would have a question since I start to understand but would like to further learn how to  modify or improve some of my reports.

I am curious how to find the connection of the conditions to the database. What I mean is f.e. "o.company_id.vat"

How can I find out to which field in which database table this expression is pointing to. This must be somewhere defined however I could not find the connection so far.

Thank you for clarifying.