It was a simple voxel data viewer I wrote circa 1997? Called pkvox.
It could load, slice, and iso-surface up to about a gig of data with only 128meg of ram. I provided C++ source to write the file format.
Thanks for your contribution! I can't find it in the usual open archives. You might want to deposit the code on Zenodo, so it gets long-term preservation and a citable DOI.
https://zenodo.org/
I'll look, but I'm not sure I even have the code any more. That was a long time ago. It had a software triangle rasterizer that pulled from a 3d voxel array to slice it. I always wanted to update it to store in 3d z-order so it would perform well on all 3 axis but never got around to it.