1. We have data of "employee" with the identifier of "emp-NO", "employee" is an entity, and it's described as noted below:

　　employee:｛emp-NO, emp-name,...｝[ R ]

　
2. If and when there is, in the "employee" set, a "partition" code of "classification by recruitment and job descriptions" with the value of "1" for "regular staff" and "2" for "part-timer", then the entity must be divided into two subsets as noted below:

[ example-1 ]

　employee:｛emp-NO, emp-name, by rct...｝[ R ]
　　｜
　　× by recuitment and job describtions
　　｜
　　｜＿＿＿＿ regular staff
　　｜
　　｜＿＿＿＿ part-timer

　
　Remember the example of business office subsets described previous time, as below:

[ example-2 ]

　Business Office:｛BO-NO, BO-name, by location,...｝[ R ]
　　｜
　　＝ by location
　　｜
　　｜＿＿＿＿ domestic
　　｜
　　｜＿＿＿＿ subsidiary abroad

　Pay attention to the symbol "×" for the "partition" code: in the example-2, the symbol is designated as "＝" while in the example-1 it's as "×."
　"＝" shows that the same format or layout (style-sheet) should be applied to the subsets--the subsets are "homotype" (or "typical"), and they are named "isomorphic" subsets("regular shape", or subsets of the same format).
　"×" clarifies that there should be a difference in format (or style-sheet) among the subsets--the subsets are "heterotypic" (or "atypical"), and they are named "anomaly" subsets ("irregular shape", or subsets of different formats).