IFLI

Taken from this site.

Multicolour-Interlace-FLI-Formats (“IFLI”): To create IFLI images, two multicolour FLI images are shown interlaced, in most cases the second image is moved by one pixel to the right to (virtually) improve resolution to 320×200. It’s also possible to increase the number of available colours, resolution then stays at 160×200.