Join Date: Sep 2005
Location: Lafayette, CO, USA
Programs: SPG Lifetime Plat, AA Gold, UA Gold, DL Silver, HH Gold, Vail Epic
Posts: 9,096
TravelGuy1965, this is not really any different than when folks use the govt or AAA rates. There's a good chance that no proof of eligibility will be required, but when it's requested, you're expected to provide it. And if you're unable to provide proof of eligibility, then be prepared to accept the best currently available public rate or the RACK rate if no rate is available.
I don't recall ever being required to provide my company ID when using my SET codes, but I have been asked to provide my AAA card or government ID (or a government letter of authorization) when using those types of rates. Should I not have such ID on me at time of check-in, I've been expected to return with such ID the next day.
If I were to use a mysterious SET code, I think that I would at least try to find out the name of the company that it belongs to. IIRC, I was once asked to give the name of my company and it's location to the check-in agent at the Westin Las Vegas. (That's a small feat to guess since my company has had three names and three headquarter cities since 2003.)