Selection tools, Enhancement tools, Vector tools, Navigation tools.
its just like classification what could be similar and has characteristics what is used on the outside is grouped saying the outside tools and the inside tools are grouped saying the inside tools.EG....
ummm......
island silicates (0 shared oxygen) disilicates (1 shared) single chain silictes (2 shared) ring silicates (aka double chain silicates) (2 or 3 shared) sheet silicates (3 shared) framework silicates...
proteins, carbohydrates, lipids, and nucleic acids thank ya