The NetWare operating system supports multiple threads running concurrently and has made extensive use of threads. Although it is possible to write a simple NLM that uses only a single thread, an understanding of threads, thread groups, and context is key to successfully creating NLMs that are complex enough to provide very useful services.
Much more complete information about threads, multithreaded programming, and context can be found in Context and Thread Groups and Context in the Threads Concepts chapter of NDK: NLM Threads Management.
NOTE:Developers of drivers, stacks, and other low-level code, please refer to Context and Development of Drivers, Stacks, etc. in the same documentation.