In Power BI, something that you often want to do is create aggregations based on filtered sets of your data. This may be aggregations based on time, such as YTD or by geography such as "Within the EU".
In DAX there are many functions available to create a filtered set of your data. Wherever the DAX function includes <filter> as a parameter, such as with the CALCULATE or FILTER functions, then Boolean TRUE/FALSE columns in your dataset can make this very easy. In the our Power BI template for Sage 50 we have added many Boolean TRUE/FALSE columns to the raw data from the Suntico BI OData feed, as well as to some additional Calculated Columns such as [IsReceivable] in the BITransSplits table. This makes it really easy to add filters to any Measures that you may want to create to perform aggregations of your data.