Do we have a consensus on what grey levels best represent the 4 available shades on the empeg display?

I'm writing a Gimp plug-in to load and save logo-screen files, and I'd like to have a suitable palette for it. I currently have {0x00, 0x20, 0x80, 0xFF} but wanted to know what others use.

I've attached my current state of the plug-in. This compiles on Linux with gimp1.2, and will read and write logo files like those distributed with "download.c" . I'm planning to add support for linking separate AC and DC images, Empeg/Rio personalities, generating blank 128x32 4-colour images (currently done in script-fu), and an integrated uploader.