From the Overview and Objectives: "This report analyzes U.S. and international sanctions against Iran. CRS [Congressional Research Service] has no way to independently corroborate whether any individual or other entity might be in violation of U.S. or international sanctions against Iran. The report tracks 'implementation' of the various U.S. laws and executive orders as designations and imposition of sanctions. Some sanctions require the blocking of U.S.-based property of sanctioned entities. CRS has not obtained information from the executive branch indicating that such property has been blocked, and it is possible that sanctioned entities do not have any U.S. assets that could be blocked."
CRS Report for Congress, RS20871
Congressional Research Service: https://crsreports.congress.gov/