Virtual Instrument file (vi or .vi)
Also see Vi , the UNIX text editor.
vi (or ".vi") is the Virtual Instrument file format. It is used by National Instruments' LabVIEW development software. LABView lets you develop applications for automating and controlling processes in manufacturing and other environments. National Instruments uses a concept of "virtual "instrumentation" to generalize and accelerate the development of this kind of application.