Earlier, the vein/muscle displacement bulked over the top of the hair displacement -- smoothing it out. Basically, there was no hair in places.
Can't reproduce it though, so it might have been just a glitch.

I know I sound like an idiot, but I am trying to get my head around it. :)

Okay... so what you're saying is, if I have any addition at a lower value, it always gets added on top?

What I'm getting at is, how does it know what to add on top? i.e. say I had the vein at 0.1 and the hair at 0.2 (for arguments sake), as long as the hair is in channel 2 of the add node, it's added to the top of whatever is displaced in channel 1?

Is that right? Or have I got myself into a total muddle trying to understand where things get added?

If I plugged the hair into channel 1 and the vein into channel 2 -- that wouldn't work, right?

Channel 1 gets displaced first, then channel 2 is added on top of that. Yes?

Silke