“Even before Barr releases the report, those planning on reading it would do well to reflect on what it is — and what it is not. It is, by regulation, a report on the prosecutions and declinations the Mueller team took during their tenure.
It is not supposed to be, contrary to many claims, a report on everything that Mueller discovered. Already there have been hints that it will not include the second half of Rod Rosenstein’s mandate to Mueller — to figure out the nature of links between Trump’s team and Russia. If that stuff is excluded, then it probably will get reported, secretly, to the Intelligence Committees and no further. That’s important because the stuff that would compromise Trump — but would not necessarily implicate him in a crime — may by definition not show up in this report (though the stuff specifically relating to Trump may show up in the obstruction case).
Finally, it’s unclear how much Mueller will include about referrals and ongoing investigations. I expect he’ll include descriptions of the things he and Rosenstein decided deserved further prosecutorial scrutiny but did not fit under the narrow rubric of whether Trump’s team coordinated or conspired with the Russian government on the hack-and-leak.”
—Marcy Wheeler, “How to Read the Mueller Report.” emptywheel.net. April 15, 2019.