Hello
Frequency lists are not part of the IVI FGen spec - it's an NI-FGEN specific extension, thus you can only access it from NI-FGEN, see:
http://www.ivifoundation.org/Downloads/Class%20Specifications/IVI-4.3_FGen_v3.0.pdf
IviFgenArbFrequency extension is simply a way to specify a frequency in which to generate a waveform in Arb Waveform Mode.
I'm not sure why you want to use IVI FGen instead of NI-FGEN, since only some of NI's Signal Generators (I'd be very surprised if another company's product implements something similar) have Ferquency Lists.
Marcos
Marcos Kirsch
Chief Software Engineer
NI Driver Software