CA IDMS Tuesday Tip by Edward Gorga, Principal Support Engineer for May 27, 2015
The TUNE INDEX utility output indicates a count for the number of records read as well as the number of SR8s processed. These counts displayed at the end of the execution can be higher than the number of records contained in the index set. This is because of the method used by the index to achieve its results.
For a full explanation see TEC1793984