The other posts are a bit off in their answer. I can confirm that Hyatt uses V1-V8 to classify its guests.
V1 is infact for high profile people as well as hyatt execs and other company execs
V2 is for VIP of the hotel itself, not so much of Hyatt as a company. Sometimes a diamond member can get a V2 based upon the hotel
V3 is the normal diamond classification
V4-V7 are for different categories of sales that will place people in.
V8 is a person who has had a problem at a hotel and the hotel has an alert to look out for this person as they have had issues at another property before or complain often.