This addendum describes the nature, rationale, and results of the second cleaning and revision of the National Longitudinal Study of 1972 (NLS-72) Postsecondary Education Transcript Files (PETS). This project, conducted for nearly 3 years, followed an initial cleaning and reduction in 1987, which came about as a reaction to the idiosyncratic records originally submitted by institutions. In this revision, the STUDENT file was left as revised in 1987, but the other files underwent considerable alteration. Four data sets with Statistical Analysis System extensions have resulted: (1) STUDENT3; (2) TRANS4; (3) TERM4; and (4) COURSE4. These include the work of the 1987 revisor P. Knepper. The revised definitions, new terminology, and renamed and altered files are described. Directions for using the modified NLS PETS files are included. (SLD)