I am seeing examples at work where we have a hierarchy, but the words don't convey the relationships. The idea is that each level contains all the items in the lower level.

E.g.,

1. Group
2. Category
3. Type

It is unclear which is "higher". I can see that people are trying to use words that make sense at each level, but they don't convey the relationship.

One could use words that clearly convery the relationship but have less meaning at each level:

1. Super Category
2. Category
3. Sub-Category

And, of course, you could do the same with many things:

1. Super Group
2. Group
3. Sub Group

Are there any examples of a good set of hierarchy terms where the meaning is fairly clear for each level but the relationship between the levels is also clear?