OKL4 Microkernels are a family of second-generation microkernels based on the original designs and implementations by Jochen Liedtke. Originally implemented in highly tuned i386-specific assembly language code, the API has seen extensive development in a number of directions, both in achieving a higher grade of platform independence and also in improving security, isolation, and robustness. There have been various re-implementations of the original binary kernel interface and its higher level successors, including L4Ka::Pistachio, L4/MIPS, and Fiasco. For this reason, the name L4 now applies to the whole microkernel family including the L4 kernel interface and its different versions.