I did not forget the article, just couldnīt spare the time to translate it. Will do, within this year. ;-)

>Could there be two completely different versions of R-100?

Not that I know of. And it wouldnīt make much sense... I believe the Fomapan R100 in our use is a side product of movie film production as the slide market is too small to justify itīs existence and the S8/D8-film lacks a decent marketing.

> The anti-halation layer in the R-100 I've used was definitely not a backing > - it was an interlayer between the emulsion and the base.

A layer of colloidal silver with a brownish cast, yep. One approach to AHU, just like Junge/Huebner list in their book "Fotografische Chemie". The others are

- greybase
- backing of carbon/resin
- backing of pigments/resin

> I've never developed R-100 to a neg though.

I did, out of curiosity. Only a sniplet, but I ended up with a negative on a brown and opaque backing. Imagine an unprocessed E6 film with a bw negative on itīs front.

I see no way of getting rid of it -without loosing the image- but a bleach and fix (or blix).