Right.

Let's consider that connecting a maths add node with a 2.2 in Value_1 to the Value_1 parameter of a color_maths pow node is copyrightable. You spent a lot of time and thought coming up with that solution and so you have the right to retain copyright if-you-wish. And, that's the pivotal point, isn't it? What do you want doing with this information? You want people to start using it, of course. Use it in their materials to compensate for (5-6-7) Poser's shortcoming in order to arrive at a vastly improved render.

Am I guessing wrong, or is this what you want to see happen?

It's about intent. This entire exercise is about compensating for a software shortcoming. Adding this feature to material for Poser Pro won't make renders better... it will muck them up. Daz Studio doesn't have this issue (to my knowledge) and besides: they can't use Poser nodes. So, this effort is targeted at a specific subgroup: Poser 5-6-7 users.

Now, going into the material room and adding some nodes so that my version of Poser 7 sees a material properly is not a problem. I can do whatever the heck I want to do with my stuff, even if I bought it from someone else. No one needs to know. I guess I'm too much of a Linux-mind to ever think otherwise: I'm a firm believer in the Open Source movement for exactly that reason. I purchase this piece of hardware to do something specific. Open Source software allows me to extend and refine that functionality to my needs, which the non-open source model doesn't support. Well, it does, to some degree (with apps like VBA for Excel and like that) but I'm not given the source code so I can't modify specific functions to my liking. We'll not discuss whether or not I want to or have the skill to - that's really irrelevant, here.

My question is this: is referencing an existing colourMap in a shader in a pz2 you intend to distribute copyright infringement? I know from having done work on hair (alternate hair colours) that referencing an existing transparencyMap is not an issue, but referencing a colourMap is - assuming, for instance, that all you wanted was to change some of the outer hair colour but didn't want to do anything to the skullcap.

Let's say I want to add a bunch of nodes (not GC stuff) to make some material appear different... say some flash specular stuff or whatever. I don't change the colourMaps or anything... just add this node set. What are my rights in terms of distributing this enhanced version? Is it up to the individual original vendor to decide whether they approve of this happening to their stuff or is there a guideline that governs what may be distributed?

Whilst I'm a firm believer in OS, I also want to protect the rights of those who have spent so much time and effort on a product, and whose livelihood depends on that product selling. I know, this sounds contradictory, but it isn't. My focus - as I said at the outset - is: what is the intent of the developer / originator / artist? I've given out heaps of freebies... all I ask is that no claim is made as to originatorship (if that's a word). I've also sold software (written in FoxPro) and had people share it around and even have the audacity to ring me up for support.
I do see some potential pitfalls in sharing material sets, however. Let's say I buy Hongyu's Jersey dress. I GC all the materials and wow, what a difference. Then, I buy a texture add-on for the Jersey dress. Well, heck, I'll go ahead and GC all those materials as well. Now, being of a generous nature, I want to share this all with other artists.

Oops. Do I need to go one? The texture add-ons (gamma-corrected) are a product on their own. They are a bunch of pz2 files: no obj or cr2 or anything. So, what is to keep people from waiting until someone buys a copy of the texture add-on, GCs it, and shares it? That poor artist that made the original texture add-on loses out.

So, what do we do? Is this a valid concept (based on this scenario) to share this sort of thing? I don't think so...

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