1. If and when there are "partition" codes in a set, subsets shall be described in a hierarchical structure:
　the levels in the hierarchical structure are fanned out by the number of "partition" codes, and subsets are created in the hierarchical structure on basis of "inclusive relationship"--a bigger includes a smaller.

2. After we draw a diagram of subsets, we must verify that the structure is valid, there're two rules for validation:

　(1) "IS" can be applied in the relation between a set and a subset like, "a subset IS a set" as noted below;
　　　- A "domestic office" IS a "business office"
　　　- A "subsidiary abroad" IS a "business office"
　　　- A "regular staff" IS a "employee"
　　　- A "part-timer" IS a "employee"

(2) "OR" can be applied in the relation between/among subsets as noted below;
　　　- A "domestic office" OR a "subsidiary abroad"
　　　- A "regular staff" OR a "part-timer"

3. If "AND" relation may be observed between/among subsets, they are NOT subsets, and the "partition" code(s) cannot be left in the set.