_System_Foundation is a cross-import overlay that bridges the low-level System module with Foundation. It provides the interoperability layer that lets file paths, errno values, and POSIX-style system primitives from System work alongside Foundation types. The overlay defines no public types of its own; it exists to connect these two modules on iOS, macOS, tvOS, watchOS, and visionOS.
This module re-exports or extends other frameworks; it declares no public types of its own in the synthesized interface.