manipulating Windows' "Open With" function.

[kokok]

Hi,

if you are using windows as your operating system, when right click on a file, there is a menu for "Open with...", and then in side that menu, there is a menu for "Choose program..." When you select "Choose program..." a dialog with the name of "Open with" pops up. In there you can choose programs from "recommended programs" or you can choose programs from "other programs" section.

I am wondering how does Windows know what the recommended programs are?
also if somebody was to write a diagram or program that shows recommended programs for a file, how would this be written in c++ code?
the compiler im using is vc++ 6.0's compiler.

thank you guys very much in advance.
I appreciate your help.