Some Entities (Materials and Jobs) can each be grouped together into "Sets" to organize them better. Sets therefore play a similar same role as folders in an operating system environment, for example.
There are two types of sets, unordered and ordered. As the names imply, an unordered set contains entities without any order and may contain nested sets. The sets are created unordered by default. On the other hand an ordered set includes one-level set of entities with a specific order.
The type of entity set can be changed following these instructions.
The order of entities inside an ordered set can be adjusted following these instructions.
Entities (and other Sets as well) can be moved to Sets following these instructions.
New sub-sets can be created inside a parent Set. Iterating this operation results in a nested directory structure.