No worries, and I appreciate the clarification.
So parallax occlusion is an enhancement of the parallax mapping technique. Parallax occlusion mapping is used to procedurally create 3D definition in textured surfaces, using a displacement map (similar to a topography map) instead of through the generation of new geometry.
I created a tutorial for how to set up parallax occlusion mapping, and a simple example of how it can be used. I am not 100% sure if you can use it for decals since they are unique in how they behave compared to regular materials.
Parallax Occlusion Mapping
In my case I actually just used a mesh I created which has some curvature, and applied the material to the mesh. You can “pull” or “push” the effect to achieve risen or sunken look.
If you want to stay on the route you are working towards, remember you can always layer materials (advanced) and then use a number of material instances to use a large number of vector parameters that are all tied to one master material as well.
Cheers,