After further testing, measurement document restrictions are based off of measuring points. There are no standard authorization checks restricting on plant occurring when creating a measurement document via IK11.
However, if an authorization group is maintained within a measuring point in IK02 or IK01, when creating a measurement document in IK11, a standard authorization check occurs based on the authorization group of the measuring point the measurement document is referencing. Maintaining authorization groups for measuring points is an option to restrict the measurement documents in IK11 or even IK34.
– SAP Security Help