I don't fully understand how all the icon data is stored in the ic0n chunk in PNG icons. Specifically I'm not sure Icon Library hard codes the icon type attribute in ic0n chunk.
According to Icon Library code if type = 0 it will deduce the icon type based on several criteria.
To better see exactly what data is in the icon files I'm writing a small tool 'IconInfo' that will list at the command line everything about Classic Icons & PNG icons.
So then I will know if Wanderer is not being truthful.
So far I looked at the icOn chunk data for about ten PNG icons. The results are surprising!
None had Icon Type defined in the attributes. Drawer icons had some drawer data & stacksize = 4096 & frameless whatever that is. Project icons had stacksize, frameless, iconx, icony & defaultool defined. Strangely, disk.info only had drawer data, stacksize, frameless & two tooltypes. It looks like a drawer icon.