In Foxtools.chm you can find few lines about this:

Fll32_16.dll is used for calling 16-bit DLLs under win32s. It uses the universal thunk to call 16-bit DLLs.

Ddereg.exe is used for calling 16-bit DLLs under win32. It uses DDE to call 16-bit DLLs.

You can find usefull some functions in Foxtools.fll, which have no analogues in VFP 7, but some of them can be replaced with API calls:

MkDir(), RmDir(), Words(), WordNum(), NextWord(), RGBComp()...

THERE ARE SOME UNDOCUMENTED USEFULL FUNCTIONS ALSO.

Nik