.spb are binary files so that's why you see all those strange characters in a text editor. Any programming language can write binary data so we don't really know or care for that matter if it was done with c# or c++, etc.

But I think this is an icon resource file of some kind that SimIcons reads so it knows how to load its data into its panel.

I was hoping there was some kind of config file that would allow me to move the icons around the panel matrix.