I use it to output bitmap halftones and dithered halftones made in Photoshop since I don't have a rip and if I want to skip using Ghostscript out of Windows (I'm on a MacBook). If the halftones are seps from multiple channels, I drop one into a 13 x 18 page in InDesign, add my registration marks and center line marks and a small color info text box just above the image box with the color name for that sep, then duplicate the page for however many seps there are, then go to each page, click on the box that has the first sep in it, hit Command D to "place" the next sep. Falls right into registration with the first sep/page, change the color info in the text box I made, and repeat. You can leave your seps in native Photoshop format if you've separated the channels to individual files, such as bitmap halftones. Otherwise I guess you'd use DCS2 as a format if you're outputting a composite file to a rip or "printing" to a .ps or .pdf to output through Ghostscript.