.upgrade file format

Can someone summarize how the .upgrade file format is constructed? File reports this is binary data, I'm hoping it's just some form of filesystem image that contains a standard script executed by the player, but I don't know this - Mark however will know because he created custom ".upgrade" images for his hijack kernel

The reason for asking is that I don't have Windows handy and I want to run a builder against a disk in this empeg unit from a Linux host. Once I know how this file is constructed, I can do it.

Jon.

Does the source code here help?

Here's a fresh copy of upgrader.c, the Linux .upgrade file processor I wrote, which can also extract/replace individual members of the .upgrade set.

Cheers