Portable Operating System Interface: The collective name of a family of related standards specified by the IEEE to define the application programming interface (API) for software compatible with variants of the Unix operating system, although the standard can apply to any operating system.

Consider the following scenario. A Portable Operating System Interface (POSIX) application declares a dependency on one or more legacy libraries. The legacy libraries are included with Utilities and Software Development Kit for Subsystem for UNIX-based Applications in Windows Vista. You run the application. In this scenario, you receive the following error message:

Library_name.so not valid NT PE file