The SIPP public use files are sorted by SSUID, EPPPNUM and SREFMON. However, in the 2001 Panel, waves 3 through 8, there are about 100 SSUIDs where the sort doesn't hold. This occurs when someone leaves the sample and re-enters in a later wave. These cases are added at the end of the queue and that sort is used to create the public use file. We will fix this for the 2004 Panel but don't plan to reissue the core wave files for 2001. The 1996 Panel is correct.