Comment by Propelloni

It's an OS built around a verified and formally proofed L4 kernel, ie. a microkernel like QNX or MACH. The L4 is a venerable design reaching back at least 25 years, if not longer. It has seen commercial and research uses, e.g. the SIMKO3 mobile phones or the Fiasco distribution. The term "task" is specific here. Running Linux as a custom operating system is a task in microkernel lingo.