S100RMSS-OS (or S100 ROM Mass Storage System - Operating System) is a component of the International Components for Unicode (ICU) project. It is an operating system for embedded systems that are written in C. It includes support for various kinds of hardware, such as Real Time Operating System (RTOS) and other peripheral interfaces. It also includes Unicode support for various languages and provides various application and development tools. Additionally, it provides expanded API sets for API and development extensions. S100RMSS-OS is intended for use in industrial and commercial applications.