I just did a dummy booking using VSA & the rate rules say nothing about showing corp id, just the usual cancel by 6pm thing, so I do think it's a publicly available rate. As a comparison I plugged in IBM as a code & the rate rules on that do say be prepared to show corp ID. I actually did a dummy booking for both a domestic & international property using VSA & IBM. Visa, no id requirements; IBM yes.

Cheers.