OCE.5:10 - Rationale

A position is useful because it persists across ordinary holder and Work changes. That persistence requires an organization-dependent identity rather than a label or person. Expected contribution and eligibility provide the stable organization-design content; establishment and continuation provide institutional force.

Keeping the position separate from U.SystemRoleAssignment also preserves cases where an assignment has no position and cases where a position is vacant. It lets A.2.1 retain exact assignment species while OCE supplies the domain subject needed by organization design.