-nomap is an Operation Flashpoint Startup Parameter, which forces OFP to avoid memory mapping for file access.
Flashpoint only. This 'switch' has no effect for Armed Assault and is not relevant for, Armed Assault. Potentially, use -maxmem for similar intended results.
While memory mapping is very efficient from a performance point of view, it can quickly fill all available virtual space, causing various memory allocation errors or even driver crashes or freezes.
This switch is especially important for users with display adapters with large amounts of VRAM (128MB or more), which reserves a lot of virtual addresses in the application address space for themselves.