sentences:  A 2010 report prepared for NIST by the Research Triangle Institute analyzed the economic value of RBAC for enterprises, and estimated benefits per employee from reduced employee downtime, more efficient provisioning, and more efficient access control policy administration.In an organization with a heterogeneous IT infrastructure and requirements that span dozens or hundreds of systems and applications, using RBAC to manage sufficient roles and assign adequate role memberships becomes extremely complex without hierarchical creation of roles and privilege assignments.Newer systems extend the older NIST RBAC model to address the limitations of RBAC for enterprise-wide deployments.