How to associate an action with an extension

Hi all,

I would need the installator to associate an extension (e.g. .abc) with a program (e.g. C:\Pgm\ABC.exe). I.e. to supply user's manual associating file Explorer's "Open with". I need - after installation - when user clicks an .abc file, than the "C:\Pgm\ABC.exe %1" to be launched.

That probably means to perform an operation with registers, but what?

Thanks,

LuP

It's all described here: