Right.

So, I'm trying to learn Shader Mixer, Daz Studio's answer to the Material Room. Purpose of the exercises: to determine whether one can draw on Poser Material Room node behaviour understoods or not.

It's probably: or not.

In any event, I'm trying out the BB setups from scratch: an excellent exercise, really. Trying to remember what the heck we were trying to understand with these shader setups. Like this one:

In Bagginsbill's words:

We start on the right with some color map - whatever original texture.

The middle Color_Math:Subtract is finding out how the texture map differs from some reference color. Here I actually sampled a color from the texture itself.

So the subtract is producing positive and negative delta colors (colors that represent the difference between two colors). The more the texture is different from the reference color, the more positive or negative the delta color will be. We cannot "see" the negative delta colors, but they are there, for sure.

The next step, on the lower left, is where I multiply the delta with a factor. If I use a factor less than 1, I decrease the delta color intensity. If I use a factor greater than 1, I increase the delta color intensity.

Finally, in the upper left Color_Math:Add node, I add back the reference color.

When the same color is used in both the subtract and the add, this serves to simply control the intensity of color variation, around that reference color.

However, when I add in a color that is different from the subtracted color, then I can actually shift what color this produces in the final output.

Which I understood this way:

The first point of this exercise is in this part of the explanation:

the subtract is producing positive and negative delta colors (colors that represent the difference between two colors)

...which can be hyper- or hypo-colours, which we can't appreciate visually, but just subtracting the control colour from one sample (dropper) of your image and chances are you're going to end up with a number below 0:

123, 149, 56
minus
127, 163, 72
equals
-4, -14, 16

Here's my version:

Then, your control bit is the Math_Function(Add) value, with which you regulate just how much of the colour you're going to add back. Which is going to affect those deltas, isn't it? Never even really thought about it (although I should have, since that was the point!), but since the deltas are pretty much an unknown, making that value something other than 1 is going to produce some interesting (read: unpredictable) results, isn't it?

Anyway, here's the deal in DS. Whether or not I did this accurately is another matter, but I've tried to reproduce the node-set in bricks:

Not the same results. Interesting.

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks