Publishing Groups
By default, all sources are assigned to a default publishing group and the hierarchy levels and measure grains are all published at the same time. Publishing groups allow you to group sources together that should be loaded separately from other data. From Modeler Prepare, you can view which additional publishing groups, if any, that the source has been assigned to by hovering over a source.
For example, you might use a publishing group if data from the source systems is ready at different times or if you would like to build an aggregate table via an ETL Services script that uses hierarchy and measure data that you have just fully published.