Now that's an interesting information challenge. Stretching my google-fu to the breaking point, the clues I've been able to find suggest that it is, or is a close cousin to, a rapid access imagesetter film for graphic arts pre-press applications. Probably relatively high contrast compared to the materials we typically use for pictorial applications.
EDIT: I went to look at your website and saw the kind of work you do and the range of processes you use. Perhaps you will be able to make something interesting of it - good luck!