DosFlatToSel

This converts a 32 bit flat address to a 16:16 far pointer to be usable by 16 bit code. This routine is callable from 16 bit code. The result is returned in eax (selector=high word, offset=low word).

Syntax
void far* DOSFLATTOSEL(ULONG eax)

Parameters

 * eax (register) : The flat address to be converted. This argument is not passed on the stack.

Timur Tabi Comments
These are 16-bit and 32-bit conversion functions. They convert pointers in one memory model to another.

I don't think they're part of the OS/2 API; rather, they are part of the compiler's runtime library. C Set++ has them also.