There needs to be an "ISALL" or "ISTOTAL" DAX function that would return TRUE if the DAX is being calculated in a total row of a matrix or table visualization, for example, and FALSE otherwise. This ...
With Power BI's heavy focus on Self Service BI capabilities, I think this is very necessary, so that we can adapt to a model where data model designers can create measures such that users can fully rely on those to use the accurate totals without worrying about what fields they are using in rows/columns of the matrix table.
