本标准定义了POSIX的扩展。1{2}以支持源代码级别的应用程序可移植性。它旨在供应用程序开发人员和系统实现人员使用。 本标准的范围是为具有实时约束的应用程序定义一个便携式应用程序接口，这些实时约束要求能够从应用程序本身控制特殊设备。 其目的是采用现有的实时操作系统实践，并将其添加到POSIX标准系列中。具体来说，本范围内定义的接口不排除在传统单处理器实时系统以及多处理器上的高性能实现。接口定义中尽可能包含其他应用程序环境的要求。

This standard defines extensions to POSIX.1 {2} to support application portability at the source-code level. It is intended to be used by both application developers and system implementers. The scope of this standard is to define a portable application interface for applications with realtime constraints requiring the ability to control special devices from the application itself. The intent is to take existing realtime operating system practice and add it to the POSIX family of standards. Specifically within the scope is to define interfaces which do not preclude high-performance implementations on traditional uniprocessor realtime systems, as well as on multiprocessors. Wherever possible, the requirements of other application environments were included in the interface definition.