I knew it as the FJX, and as originally drafted it was very close indeed to the CRJ-100 in size, passenger capacity and range. Looked a bit like a smaller Airbus A319. It was first promoted to North Amercan carriers in early 1988 (with that mock-up you mentioned?), before Canadair froze the CRJ's design, and about a year before the final launch decision for the CRJ was taken.