Plate of connections
Materials, building systems, processes and regulations are not four parallel lists: they are one graph. A material leads to the systems that use it, those systems to the regulations that govern them, those regulations to other materials. This is where you step in and start walking.
The number beside each entry is how many other nodes touch it: a measure of how much that node holds the network together. Open it to see its plate, and carry on from there. Every plate has its own address, so it can be linked and cited.