lpReserved2

lpReserved2 is a field name that appears in some Windows internal data structures used to manage process startup information. It is not part of the documented public Windows API, and its exact purpose, type, and behavior are not officially described by Microsoft. Because the field is part of internal OS structures, its presence and semantics can vary between Windows versions, and information about it is often found only in reverse-engineered sources or private headers rather than official documentation.

In practice, lpReserved2 is typically treated as opaque by application developers. When it appears in internal structures, it is usually described as a reserved pointer or placeholder for potential future use by the operating system. The lack of public documentation means that relying on this field for application logic is discouraged, and its contents should not be assumed or manipulated by user-mode code.

Guidance for developers is to avoid reading or writing lpReserved2 in production software. Access to internal fields like lpReserved2 can lead to instability, incompatibility across Windows updates, and violations of supported programming practices. If encountered in code samples or debugging contexts, treat the field as reserved and non-deterministic from a public API perspective.

See also: STARTUPINFO.lpReserved, RTL_USER_PROCESS_PARAMETERS, PROCESS_PARAMETERS, PEB, Windows NT native API.