DosSelToFlat

This converts a 16:16 far pointer to a 32 bit flat address to be usable by 32 bit code. This routine is callable from 16 bit code. The result is returned in eax.

Syntax
ULONG DOSSELTOFLAT(void far* eax)

Parameters

 * eax (register) : The pointer to be converted (selector=high word, offset=lowword). This argument is not passed on the stack.

Timur Tabi Comments
This 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.