Bot material from the Infiltrator question (SETUP)

Hi all,

I have been looking at the bot-material setup from the infiltrator demo and I’m wondering
how this is setup. I have noticed that there are RGBA channels for example spec/ao/emmsive
and more. My question is the base/diffuse texture just a plane base color node/parameter? and then
its uses the channels for the ao/spec/gloss/emssive stuff? this gets put on top of the base/color?
Is this how it works?

because I was looking for the difusse/base texture in the material instance but there are only slots for
detail/blend/normal, etc. Does anybody know how & were I could find the difusse base texture or
is it just a color /node paramater?