How does ERISA define "parties in interest"?

ERISA prohibits a wide variety of transactions with a "party in interest" with respect to a plan:

• A fiduciary;
• A service provider;
• An employer any of whose employees are covered by the plan;
• An employee organization whose members are covered by the plan;
• A 50% or more owner of such employer or employee organization;
• A spouse, ancestor, lineal descendent, or spouse of a lineal descendant of any of the persons above except an employee organization;
• A corporation, partnership, trust or estate of which 50% is owned directly or indirectly by persons above (other than relatives);
• An employee, officer, director or 10% or more shareholder of any of the persons mentioned above except a fiduciary or a relative; and,
• A 10% or more partner or joint venturer of any person above except a fiduciary or relative.