What are the relationships among enterprises, organizations, accounts, sub-accounts in CloudOS?

An enterprise (created via the primary account) can have multi-level organizations (up to 5 levels). Multiple sub-accounts can be attached under each organization, and multiple IAM users can be created under each sub-account. Among them, the primary account is responsible for managing the entire enterprise, sub-accounts serve as actual users and administrators of resources, IAM users refer to specific operators under sub-accounts.