Comment 1: Types of subsets can include:
customer subset
initial customer subset
project subset
initial project subset
product subset 
business unit subset
application subset
environment subset
security subset
Comment 2: Items identified by subset owner in effect comprise another type of subset, but the inclusion of a separate data category for this distinction as a subset identifier would be redundant. Instances in this subset group are combinable and mutually independent, i.e., the same entry can require the inclusion of multiple subset identifiers.