Special Considerations for 16-bit Windows-Based Applications

16-bit Windows-based applications may call the exclusive volume-locking IOCTL functions directly using the Interrupt 21h interface, which is described in the reference material. These applications must mark all of the code, data, and resource segments that will be accessed while inside the level 2 and 3 locks as PRELOAD NONDISCARDABLE in the module-definition (.DEF) file. This marking prevents deadlock in case the system needs to load one of the application's segments from the executable file inside a level 3 lock.