To gather more information concerning the use of IVI there is a very comprehensive page of Class Specifications for IVI Class Instruments:
www.ivifoundation.org
This resource covers all IVI calls for each class of instruments and should provide you wiht valuable information. For an additional overview of IVI and its relationship to NI products, you can also visit our Resource Library:
ni.com>>Resource Library>>Instrument Drivers
Best Regards,
Chris D
Applications Engineer
National Instruments