# Operating System Layer The OSL (Operating System Layer) allows cross platform access to common operating system features but that are accessed differently depending on the platform. The OSL consists of a series of C++ classes, backed by a C-based API for maximum portability. This was necessary when Star Division started because many of the things needed, such as mutexes, condition variables, threading, time functions and a variety of other operating system specific mechanisms hadn't been produced by libraries such as the STL, and certainly what there was couldn't be used as a cross platform solution. As the C++ Standard Template Library has matured, there have also been other libraries that work in a cross platform manner (such as [Boost](https://www.boost.org/)) and so large parts of the OSL (or all of it) is largely better handled by these libraries. The following will discuss the functionality implemented in the OSL, with a comparison against more modern, cross platform C++ libraries. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://chris-sherlock.gitbook.io/inside-libreoffice/system_abstraction_layer/operating_system_layer.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.