If you choose Composite Gray in your Print/Output dialg can you check Negative or is it grayed out?
Some of my printers allow this. Some of them do not if the printer driver does not allow it to be set as a CMYK device.
Another alternative short of a RIP is to print a PS file and select negative then distill to PDF and place into ID and then print using Composite Gray with the RGB print driver.
Yes - that is exactly what happened. The printer we need to access for output is connected to the computer that will not allow it. I'm going to try the PS file procedure and see how the quality holds up. The crew reassembled the entire thing in Illustrator while I'm here researching so it's on the move. But I want to be sure I know all my options for InDesign.