This is makeindex, version 2.17 [TeX Live 2024] (kpathsea + Thai support).
Scanning input file refman.idx....done (44 entries accepted, 0 rejected).
Sorting entries....done (239 comparisons).
Generating output file refman.ind....done (101 lines written, 0 warnings).
Output written in refman.ind.
Transcript written in refman.ilg.