I have a 3-digit, 7-segment+decimal display I bought from an ebay store. I believe it is a hi-eff red one, and the seller provided this link to the data sheet. A search found this data sheet which is more complete and seems to describe the part better, though bottom line - I don't know exactly which part I have. The part has "C403E (1) T0831 RoHS" printed on one edge.
I checked each segment as I wired them on a breadboard, and when I inadvertently powered one without its resistor, surprise! It glowed green - not overly bright, and didn't burn out. I repeated this with, and without its resistor; with a resistor it's red, without one, it's green.
Anyone know why / how this could happen? Every bi-color, common cathode part I've been able to find has two anodes per segment. This one has only one.