[nworth]

In the late 1970s I used a 35mm Kodak direct positive B&W film marketed for scientific use, and not generally available in stores. As I recall, it was red until developed, and very slow, maybe ISO 3. It was developed in Dektol print developer. Another way to make B&W positives is to copy negatives with a high contrast film like the late Kodak Tech Pan.

This sounds like one of the many Kodak Autopositive products. They were marketed as part of Kodak's Reprographic line through blueprint and industrial dealers. Most were extreme contrast materials. I remember the papers had to be exposed through a yellow filter for the automatic reversal effect to work.

There was also a special order medium contrast automatic reversal material available for several years (I think in the 80s or 90s). It was also developed in Dektol and had about that speed. It had a number of industrial uses and was particularly popular for making enlarged negatives for contact printing. It had a rather high inherent fog level, which limited its usefulness and quality.