HITRUST scoping boundaries help organizations define how their environments are assessed. The Shared IT services boundary is used when scoping common technology services and supporting infrastructure (e.g., hosting platforms, networks, identity services) that serve one or more business units. This contrasts with Follow-the-data (traces data flows across processes/units), Enclave-focused (a discrete segmented environment), and Enterprise (the entire organization).
"Shared IT services boundaries encompass the common IT platforms and supporting infrastructure leveraged by one or more business units." [CCSFP Study Guide - Scoping Boundaries, 0155]