L3 is a microkernel operating system on Intel x86 - based. It was designed as a "very lean and features fast, message-based, synchronous IPC, simple- to-use external paging mechanisms and a security mechanism based on secure domains (tasks, clans and chiefs ) ."
L3 is the predecessor of L4, a microkernel with a similar concept. The system was developed as a fully open, non - graphical operating system by Jochen Liedtke and his team at GMD - Research Center for Information Technology. Written it is almost completely in the structured programming language ELAN. Exceptions are the kernel as well as some hardware drivers in assembler and CDL2. It is since 1992 at TÜV Süd in use.