Olivier Van Steenlandt does some documentation:
In this blog post, I will guide you through all the required steps to get a Data Model Relationship Matrix in Power BI.
If you don’t know what I mean, I would like to have a straightforward overview where I can see which attribute groups and measure groups I can combine from my Tabular Model in (SQL Server) Analysis Server.
The first thing I thought of was “this is very much like a bus matrix in the Kimball model.” It’s a little different, though, as the rows in the axis pertain to measure groups rather than business units.